Not much is known about Casey Jones, except for the fact that he clearly knows about the existence of mutants. Casey has created his own arsenal of weapons, which he uses against his enemies; mutants and criminals alike. It is hinted that he has been down in the sewers and he might even have his own lair set up down there. In the online comic, Casey had spray painted "Jones is Everywhere" with his iconic hockey mask tagged next to it, possibly indicating that he goes go down there occasionally.
- Mutagen Man Unleashed - In his debut-episode, Casey encounters April in the hallway where he tells her that she's his tutor. Even though he proved he would be difficult to work with, he says he's willing to cooperate if it means staying on the hockey team. April agrees to help him and decides to tutor him that night in the park. When they start their session, Casey tells April that he's not interested in trigonometry and wants to be a hockey player or a bounty hunter once he graduates. Despite everything April had witnessed that day, he surprises her by asking who wants to live a normal life. When April sighs a bit, Casey shows empathy. He then notices a smudge on her face and wipes it off, which shocks Donatello, who is watching them from a rooftop. On their way back home, Mutagen Man shows up and tries to approach April. Casey steps in front of her and manages to get a couple of hits in. However, he and April barely fend him off, but they are able to shake him off and escape unharmed. They make their way back to April's apartment while watching out for anymore mutants. They make plans for their next tutoring session just as Mutagen Man prepares to go after April. Casey almost heads towards the alley where the Turtles are fighting Mutagen Man when April redirects him to the other way.
- Target: April O'Neil - He meets April in the hockey ring where they strike up a conversation. He asks her why she doesn't hang out with other people, which results in her telling him that she and her friends "are fighting". He relates her situation to his friendship with his best friend Nick ending after he accidentally injured him during a hockey game. Even though both say that Casey didn't mean to hurt him, he repeats that it was something that was beyond his control. Just then, when Casey goes to change, the Foot Bots attack April. He shows up and starts fighting them off while telling April to leave him. Despite his wishes, April helps him fight the soldiers and leads a few away. After the Turtles defeat Karai and her robots, April returns to the ring to find Casey unharmed.
- The Good, The Bad and Casey Jones - Casey first met Raph when he's fighting 3 members of the Purple Dragons, when Raph tries to stop him from possibly killing them. The next day at school, April wonders what's wrong with him since he got quite a lot of bruises from the fight, which he claim is from practicing hockey. He then was brought to the Turtles' lair and found out about the secret and everything. He later fought a Foot bot with Raph and ended up being friends and joining the team.
- Fungus Humungous (episode) - Casey is seen at the beggining of the episode reading a paper with April and she says it's nice to have someone else to know the secret about the turtles. He later falls under the spell of the fungi and sees many rats as that is his fear but in the end he is cured.
- Of Rats and Men
- The Manhattan Project, Part 1 - First he gets eaten by a Kraathatrogon and later rides one with April to stop the Kraang
- The Manhattan Project, Part 2
- The Lonely Mutation Of Baxter Stockman - He rides Kirby Bat with April to get her father cured.
- Newtralized! - Casey follows the turtles and destroys the Kraang Walker, defeating the Newtralizer.
- The Wrath of Tiger Claw - Casey gets severely injured by Tiger Claw.
- Plan 10 - Casey gets his mind switched with April.
A Chinatown Ghost Story - It's shown he has a metal plate on his skull. The Invasion - Casey Jones and Raphael are looking for Karai on the rooftops. Casey asks Raphael, while looking at some graffiti he did, if April ever talks about him. Soon some cops come and try to arrest Casey. He hits them with a Hockey stick revealing them as Kraang Droids. Soon he and Raph make it to April's house. After Leonardo comes crashing through the window, they hop into the Party Wagon. Casey drops April, Donatello, Michelangelo, and Raphael off at the base, while he looks for his little sister and father. Casey delivers a blow to Kraang Prime by driving the Party wagon into his suit. Then Casey, Raphael, Michelangelo, Donatello, April, and an unconscious Leonardo drive away to the O'Neil farmhouse. Casey talks to April about how the Kraang probably got to his father and sister because he couldn't find them anywhere.
- Within the Woods - The Creep attacks him and gets his hockey mask.
- A Foot Too Big
- Buried Secrets
- The Croaking
- In Dreams - Casey and April investigate Bernie's General to save the turtles.
- Race with the Demon - Casey and Donatello build the Turtle Racer to defeat the Speed Demon.
- Eyes of the Chimera - Casey, Mikey and Raph are abducted by the chimera.
- Vision Quest - Casey and April stay at the farmhouse training.
- Return to New York (2012 TV series episode)
- Serpent Hunt
- The Pig and The Rhino
- Battle for New York, Part 1
- Battle for New York, Part 2
- Casey Jones VS. The Underworld - After being left out of the action in the battle for the city and losing a fight against the new Purple Dragon leader Hun, Casey decides o clean the city on his own spying the Foot and the Dragons.
- Meet Mondo Gecko - Mikey and Casey befriend Mono Gecko, but Mondo's actions make him angry and he leaves them alone. Later the three of them have to race Fishface to the death.
- The Deadly Venom - Casey, April and the turtles are poisoned by Karai.
- Tale of the Yokai- appeared briefly in a photo the turtles had. he and April nearly vanished as the turtles attempted to save Splinter and not mess with time.
- Attack of the Mega Shredder! - Casey Jones Attack With April And Donnie And Raph and April Mega Shredder By Turtle Mech.
- Annihilation Earth! Part 1 - Upon learning of the impending invasions by both the Kraang and the Triceratons, Casey joins April and the Turtles with attacking the Technodrome, and then the Heart of Darkness when it is deployed in Washington Square to be used on the Earth.
- Annihilation Earth!, Part 2 - Casey is captured with the Mutanimals when they attempt to shut down the Heart of Darkness, only to be rescued later, but is unable to stop the Black Hole Generator from being activated when Shredder murders Splinter. Luckily for Casey, he, April, and the Turtles escape Earth's destruction thanks to the Fugitoid. Casey is excited to be heading out to explore the universe.
- Beyond The Known Universe - As the Fugitoid turns back time six months to allow the Turtles, April, and Casey a chance to prevent Earth's demise a second time with finding and destroying the Heart of Darkness, they set course for another part of space. When the Ulixes is damaged by asteroids, as the gang suit up in spacesuits, Casey finds one that is equipped with high-tech photon hockey pucks for him to use in place of his homemade ones. After landing on the planet Varanon so the Ulixes can be refueled and repaired, Casey and Raph make the mistake of accidentally decapitating the robot merchant of a weapons store, causing the security robots to chase after them to pay for the damages, before fleeing when the gang run into Lord Vringath Dregg, who takes Casey prisoner for disrespecting him and prepares to eat him before the Turtles and April intervene, destroying Dregg's latest purchase by accident, further angering him so he sicks his Vreen on them, then overpowers them personally, forcing them to flee back to the Ulixes and escape. Dregg gives pursuit, and manages to get one of his Vreen aboard, but Casey kills it with a photon puck. However, though they escape Dregg, they end up face-to-face with the Triceraton Armada.
- The Moons of Thalos 3 - An encounter with a Salamandrian fighter that had been engaging the Triceraton Armada leads to both it and the Ulixes crashing on an icy moon, where if the Fugitoid can not find the material he needs to fix the Ulixes before the life support in everyone's suits run out, they could all perish on the moon. After running into the Salamandrians who were in the fighter that crashed with them, the Turtles and the Salamandrians soon form an uneasy alliance to get the material the Fugitoid was looking for back to the Ulixes, with Casey sacrificing his photon pucks to stop a herd of Ice Dragons from pursuing them, but once back at the Ulixes, their life support finally runs out. However, the Fugitoid is able to repair the ship and get everyone inside just in time, saving Casey and all their lives. Casey and the Turtles depart on better terms with Y’Gythgba and G’Throkka, hoping to see them again in the future.
- The Weird World of Wyrm - Arriving at the ruins of an abandoned spaceship, as they explore the inside of the ship, Casey humorously makes a wish to battle some zombies. Unknown to him, the ship was home to the hyper-cube prison of a genie-like creature called Wyrm. When Casey finds the cube, Wyrm grants his wish and revives the dead crewmen as zombies to fight Casey and the others. They manage to escape back to the Ulixes with Wyrm's prison, and despite orders not to touch it, Casey does, and releases Wyrm. After, Donnie makes a second wish, for Casey not to be such a big dummy, which makes Casey become super-smart, then the Turtles make the mistake of making a third wish, thus freeing Wyrm, who beings to take over the Ulixes. Worse, Casey, with his newfound knowledge, sides with Wyrm to take down the others. However, before he kills them, Casey asks for one more wish. Wyrm, seeing no threat, grants it, only for Casey to turn the tables on him and use the wish to undo everything that's happened up to before Casey made his original wish. When he's about to make it again, April stops him, having a feeling he had better not say anything. With that, everyone returns to the Ulixes, leaving Wyrm trapped in his prison, pleading for them to make a wish to let him out in futility.
- The Outlaw Armaggon! - Casey and the others are attacked by a bounty hunter hired by Lord Dregg by the name of Armaggon, forcing them to hide in a space station where they unintentionally awaken the dormant A.I. of the station, Overlord. Armaggon has Overlord crank out an army of VX3 Warbots to capture Casey and the others, but when Overlord reveals his true intentions of eliminating organics for machines, Casey is nearly turned into a robotic drone before Armaggon intervenes, under orders from Dregg to bring them back alive. After April frees the Fugitoid from Overlord's control and he causes the station to self-destruct, Casey and the others escape back to the Ulixes, and resume their pursuit of the Triceraton Armada, not realizing Armaggon is still after them for his bounty.
- Riddle of The Ancient Aeons - Traveling to the planet that is home to the Aeons, Xaava-Dal, Casey is among those affected by the dark atmosphere of the planet as it increases his anger and hostility towards the Turtles. Thanks to April and the Fugitoid, he is able to overcome the atmosphere's influence on him, and help to restore the Aeons' Sol Star that, in turn, restores the planet and the Aeons themselves to normal. After meeting the Aeons in their true form and being thanked for helping them, Casey and the others depart to pursue the Triceratons, who got away with the first piece of the Heart of Darkness.
- The Arena of Carnage - Having caught up to the Triceraton Mother Ship, Casey remains on the Ulixes with the Fugitoid and April while the Turtles infiltrate the Mother Ship to find the first piece of the Heart of Darkness. However, the Turtles are captured, forcing Casey, April, and the Fugitoid to infiltrate the Mother Ship instead. While the Fugitoid is captured and taken before Emperor Zanmoran, he buys Casey and April time to find the main armory and retrieve the first piece, only to soon be fired upon by the returning guards. As they flee, they crash into the Turtles and Fugitoid, who had taken Zanmoran prisoner, knocking off the Emperor's crown. As the Tricertons who had been following April and Casey hold their fire upon realizing the Emperor was in the crossfire, it gives Casey and the others time to escape through an airlock, retreat back to the Ulixes with the first piece, and escaping before they can be pursued by Raptors.
- The War for Dimension X - Casey is forced to remain behind on the Ulixes with April while the Turtles and Fugitoid travel to Dimension X to speak to the Utrom Council about helping them find the remaining two pieces of the Heart of Darkness. Casey doesn't take it too well as he bangs his hockey stick against the floor in frustration.
- The Cosmic Ocean - Traveling to the home of the second piece and its guardians, the Daagons, it is not long before Casey and the others meet the Daagon leader, Hiidrala, and learn that in order to get the second piece, they need to prove themselves worthy to the Cthugga. However, the Ulixes is attacked by Armaggon, and after he commandeers it, they are soon forced to flee from the Cthugga. After Armaggon is apprehended by the Daagons, Casey and the others return to Hiidrala to be told they failed and won't get the piece. However, Lord Dregg and his Vreen arrive, and a battle ensues. After Leo protects Hiidrala from a missile from Dregg, she summons the Cthugga to devour Dregg and Armaggon. Casey watches in surprise as the Vreen, having lost their hive mind in Dregg, stop fighting and flee. With Casey and the others having proven themselves to Hiidrala, she entrusts the second piece of the Heart of Darkness to them, hoping they can destroy the infernal device, and declares them heroes of the Daagons. With two pieces in their possession, Casey and the team head after the final piece.
- Revenge of the Triceratons - Before they can reach the location of the final piece of the Black Hole Generator, Casey and the others are ambushed by the Triceraton Armada. After Casey jokes about Mozar being demoted back to Captain from Admiral for losing the first piece of the Black Hole Generator, Mozar attacks the Ulixes. After having a Rock Rocket loaded with the Skeevix Virus impact the Ulixes and decapitate the Fugitoid, Casey pokes the Rock Rocket with his hockey stick, releasing the Skeevix larvae to scamper off an find somewhere to cocoon and evolve into their true forms. Casey is forced to deal with them alongside April and Mikey, and are able to slay all the evolved Skeevix, but they are unable to overpower a trio of Raptor pilots when they board the Ulixes to retrieve the first two fragments from them. Thanks to Donnie repairing the Fugitoid, they are able to take out one, but the other two escape with the fragments. Despite the setback, Casey remains encouraged to find the last piece before the Triceratons do.
- The Evil of Dregg - Responding to a call for help from Y’Gythgba regarding G’Throkka being taken by Dregg and Armaggon to Sectoid 1, Casey and the gang travel there to rescue him, but Casey disturbs a hive of Xaxx Bees, and unintentionally smacks one into Donnie's face, causing Donnie to suffer repeated alien bee stings, and have to be taken back to the Ulixes for medical treatment by April and the Fugitoid. Despite that, Casey and the others fall into Dregg's trap, as Mona and Sal Commander betrayed them to protect their own home world. Though Casey frees them from the cage they were in while being guarded by Armaggon, Dregg knocks them into a pit to face the Scorpinoid. They manage to escape, thanks to April causing a distraction, and joined by a vengeful Sal Commander and Mona when they learn that Dregg has no intention of calling off his invasion of their home world, they are able to overpower Dregg, Armaggon, the Vreen, and the Scorpinoid, and escape Sectoid 1.
- The Ever-Burning Fire - Traveling to Magdomar, where the final piece of the Heart of Darkness is located, Casey ends up having to deal with Lord Dregg again when he chases them down, looking for payback for the Scorpinoid. Later, when Chompy Picasso gives away their position to the Triceratons, they are forced to fight them for a short bit before escaping. When the guardian of the final fragment, Tokka, awakens, Casey and April are tasked with protecting Chompy, only to discover that Chompy is Tokka's baby, and return him to her with no problems. However, when the Turtles free the final fragment from Tokka's shell, Dregg gains hold of it and delivers it to the Triceratons, who then detonate the nearby dwarf star to allow their escape, with Casey and the others barely escaping themselves. Later, Mozar contacts them to reveal his intent to use the Heart of Darkness on Earth, to the horror of Casey and the others.
- Earth's Last Stand - As the Ulixes returns to Earth, Casey is happy to be able to see his family again, but upon learning that the Fugitoid is the one who built the Heart of Darkness, he is furious that the Fugitoid deceived them. After Leo attempts a useless one-man assault on the Triceraton flagship that nearly costs him his life while the Ulixes nearly crash-lands on Mars, they return to Earth, only for the Fugitoid to dump them out of the Ulixes when they refuse to cooperate with his latest plan. Meeting up with his past self, they are able to disarm the Heart of Darkness and overpower Mozar, forcing him to retreat to use the Devastator on New York City before retrieving the Heart of Darkness to wipe out the Earth. However, the Fugitoid sacrifices himself to see to the destruction of not just his doomsday weapon, but the Triceraton flagship as well, leaving Casey to figure out what to do with two of him on Earth. Thankfully, the past Fugitoid arrives to take the past Turtles, April, and Casey into space, allowing the future Turtles, April, and Casey to return home with Master Splinter, the Mutanimals, and their other allies.
- City at War - Casey attends the ceremony of April's promotion to full Kunoichi by Splinter, and joins in the celebration with the Turtles following Splinter completing the ceremony.
- The Insecta Trifecta - With the knowledge that Shredder is still out there and a threat to New York City, Casey teams up with Raphael to patrol one sector of the city, only to soon respond to the alarm of a nearby bank that has been broken into that the NYPD sends a cruiser to investigate as well. The perpetrators of the robbery are Stockman and his two new henchmen, Antrax and Scumbug. While Casey is ready to throw down with them, he is forced to go it alone due to Raphael suffering another of his panic attacks from his bug phobia and running off in terror, leaving Casey to be overpowered and captured. Taken back to Stockman's lair, Casey taunts Scumbug before he is gagged while Stockman decides to move their lair elsewhere when Scumbug worries the Turtles will come looking for Casey and find them. As a result, Casey is taken to Stockman's new lair in a skyscraper construction site after he has kidnapped April, Leo, and Karai as well. Before Casey can be used as food for Stockman's henchmen, Donnie, Mikey, and Raph arrive to save them, but once free of the web he was stuck in, Casey is unable to help much due to being scared of heights, but in the end, Stockman flees back to Shredder in defeat while the Turtles capture Antrax and Scumbug, along with retrieving the stolen money as well.
- Bat in the Belfry - Casey is out on his bicycle, bored with not seeing some action, when he notices several civilians running for their lives. Investigating the situation, he finds himself face-to-face with Monoculus, a monster from Mikey's comic book. Sending a picture to the Turtles, he soon has their help, but all of them are overpowered except for April, who easily destroys Monoculus with her Tessen fan and her Aeon crystal. While April, Leo, Raphael, and Donnie return to the lair, Mikey stays with Casey to consider how Monoculus came into reality and think that April's Aeon crystal is behind it. When Mikey returns with it and tries to use it to bring Wingnut and Screwloose to life, Casey mocks his efforts and gets into a fight with Mikey, before both are blown back by an energy burst from the Aeon crystal that does just as Mikey hoped and brings Wingnut and Screwloose to life. After mistaking Casey for being an accomplice to Mikey, Wingnut and Screwloose allow Casey to join them and Mikey with protecting the city from crime, but when Mikey and Casey spill the beans about Wingnut and Screwloose's history, then show them the Aeon crystal that was responsible for their revival, entranced by the crystal, Wingnut and Screwloose take it, only to be transformed into more animalistic forms and flee with the crystal. Casey and Mikey tail them to a clock tower, and are soon joined by the rest of the team in the Turtle Blimp. Thanks to April hitting the church bell and thus weakening Wingnut and Screwloose, Casey is able to help keep them incapacitated long enough for April to retrieve her crystal and revert them to normal. Afterwards, Wingnut and Screwloose accept that they have to go back to their comic book world, and Casey sees them off as April returns them to their comic book, before comforting Mikey as he cries over how he enjoyed the time he spent with them and how he may never get that chance again.
- Raphael - Casey originally viewed Raphael as evil, but after finding they have things in common (e.g. liking to fight crime), they became best friends and sometimes rivals. Mostly, they work as partners in defeating any enemy that comes their way.
- Donatello - Donatello views Casey as a rival for April's affection, but still considers him an ally and as of "Race with the Demon" his friend.
- Leonardo - An ally; Casey seems to interact more with Raphael and Donatello.
- Michelangelo - Michelangelo and Casey don't interact as much as the others, but they are still allies and friends.
- April O'Neil - April hangs out with Casey in school. At first, April was tutoring Casey and after sometime they became good friends. Although it was revealed that Casey prefers to hang alone with April, he is seen to hang out with her and the turtles in some episodes. Since then it has been show that Casey and April have feelings for each other. Casey shows his emotions toward April more though by crushing on her [for example in The Invasion, Part 1 when he did some graffiti on a nearby wall of him and her together].
- Splinter - Originally, Casey was afraid of Splinter due to the fact that he has a fear of rats, but has since become comfortable with being around him. Splinter has been shown to be friendly towards Casey when meeting him, as he thanked him for helping to protect his sons (the turtles) and the lair (their home). Casey told Splinter it was no problem. Since then despite his fears, Casey has had no problem being around splinter or being in the sewers.
- Slash - Was originally wary of him due to his extremely violent nature, now they are acquaintances on better terms.
- Bigfoot - Caused her to run away into the woods when he and Leo made fun of her make-up, to which Michelangelo chastised them for.
- Punk Frogs - Casey originally hated the Punk frogs because they kidnapped and locked him and April in cages, but when the fire started he saved Attila by shoving him from the base.
- Bernie - Was originally horrified of him due to his restless nature making him look insane, but later allied with him to save the turtles from the Dream Beavers. He then took him home after he fell asleep after the whole ordeal.
- Dr. Cluckingsworth
- Mondo Gecko - Casey and Michelangelo befriended him at first, but then briefly hated him for taking money from the Purple Dragons. After surviving Fishface's, they got on better terms.
- Karai - although they haven't had any contact or interaction, He along with April and the turtles have attempted to help save her from the shredder and foot a few times. He later met her in The Deadly Venom when she attempted to hunt down him, the turtles and April by poisoning and killing them all which failed. She also kissed him as she poisoned him.
- Mutagen Man
- Rat King
- Slash (formerly)
- Baxter Stockman
- Tiger Claw
- Kraang Prime
- Punk Frogs (formerly)
- Dream Beavers
- Speed Demon
- Purple Dragons
Casey seems to be a bit arrogant, a bit flirty (at least around April), quite inattentive to his school work, and he thinks highly of himself. Even with his first encounter with April, he managed to show how involved he is with himself and the fact that he thinks little of others. But he admits that he does need a tutor, as he wishes to stay on his hockey team. And while he tended to aggravate April a bit during their tutor session, he tried in his own way to be friendly and get her to enjoy herself with something besides just books. He also shows a sense of "empathy" when she shows to be exhausted from that day, and reaches out to wipe a smudge off of her face.
During their encounter with Mutagen Man, Casey became protective over April and tried his best to watch out for her. He was also very impressed by how April fights - and he then asks if encounters like with Mutagen Man happen frequently. When she answers "too often", the idea seems to excite him.
- Custom Painted Goalie Mask
- Skull Face Paint
- Hockey Glove
- Laird's Hockey Blocker Glove - with spikes
- Homemade Taser - a potato masher rigged with 9volt batteries on a drawer track with springs
- Padlock of Doom - a lock tied up to a handkerchief
- Bunch of Keys
- Custom Sheaths - made out of belts and duck tape
- Paint Grenades - spray cans
- Wooden Baseball Bat
- Eastman's Wooden Hockey Stick
- Wooden Goalie Stick
- Wooden Cricket Bat
- Custom Skates
- Spiky Pads
- Fire Breathing Bicycle
- Hockey Pucks
- Explosive Hockey Pucks
- Protective Cup
- "School isn't always my thing. When I graduate, I’m becoming either a pro hockey player or an international bounty hunter." - Mutagen Man Unleashed
- "Do you know what this is? This is Casey Jones vs. Evil Robo-Ninjas! Coolest freaking thing in the universe!" - Target, April O'Neil
- "Goongala!". - Mutagen Man Unleashed/Target: April O'Neil/ The Good, The Bad, and Casey Jones
- "Scum-suckin' mutant freaks of the world, prepare to meet Casey Jones..." - The Good, The Bad, and Casey Jones
- "The class is Pain 101. Your instructor is Casey Jones." - Casey Jones VS. The Underworld
- "That is messed up, yo!" - Earth's Last Stand
- "Leo was right! He's useless!" - Earth's Last Stand
- "So, uh, what are we going to do about this? The Earth isn't big enough for two Casey Joneses." "Hey, back off, punk!" - Earth's Last Stand
- Casey's hockey stick has "Eastman" written over it as well as his arm protection has the name "Laird", the names of the Ninja Turtles creators.
- In The Good, The Bad and Casey Jones, it was revealed that Casey has musophobia (the fear of mice and rats), at the beginning he was even afraid of Master Splinter.
- When Casey was drawing himself defeating Raphael, it was in the style of the original mirage comics.