Irma is usually dressed in a light blue turtleneck sweater, a long, light purple skirt, white leggings, yellow socks (or red socks on two occasions), and light brown loafers. She wears large-lensed eyeglasses with bright pink frames. She wears her hair up, with a white scrunchie holding part of it in place.
Like April, Irma is one of the few humans who accept the Turtles instead of seeing them as evil just because they are different from the humans. She is klutzy, tending to stop on a person's feet whenever she gets upset.
Irma is boy-crazy most of the time, even showing affection to the Shredder in one episode (though she believed it was a man in a Shredder costume at the Mardi Gras costume parade).
"Are you single?" -- Irma Langinstein
Her first appearance was in the 1987 series, Season 2 first episode "Return of the Shredder". Through the entire second season, Irma is initially only aware of the Turtles' existence through April's connection to them, which she tries to keep from Irma to little success. In "Catwoman from Channel Six", Irma met the Turtles face to face for the first time, and has been both an asset and a hindrance to them ever since.
While her charm, romantic spirit, brash sarcasm, and shy attributes define her strengths, Irma also suffers from a case of severe clumsiness, and her obsession with finding a romantic partner eventually reduces her to craving for monsters, mutants, and even the Turtles themselves at one point. She bonded the most with Donatello during the course of the series.
After Channel Six's destruction during season eight, Irma is gradually phased out with the remaining Channel Six crew despite continuing to operate from a different, and less luxurious, accommodation. She was terrified and shocked when Burne Thompson blamed the destruction of the Channel 6 building on the turtles, turning them into wanted outlaws. Her final appearance was in "State of Shock".
After meeting the Turtles, Irma has had some various adventures with them, as well as misfortunes happen to her.
- In "Attack of the 50-Foot Irma", it is Irma's birthday and she is accidentally enlarged by an enlarging ray powered by Exaporon, by Krang (who meant to fire the beam at Shredder). Upon being giant, Irma's clumsiness gets the better of her. Eventually, the Turtles manage to shrink her back to her normal size.
- In "Green with Jealousy", Leonardo, Raphael and Michelangelo were under the influence of a love potion and fell in love with Irma. Irma was happy to get presents from her secret loves until she found out that all of them were from the turtles.
- In "Were-Rats from Channel 6", she's mutated into a rat and mind controlled by the Rat King, along with Vernon.
- In "The Turtle Terminator", while preparing for a date with an anchorman at Channel 6, Irma is kidnapped by Bebop and Rocksteady, and replaced by a Turtlenator robot that disguises itself as Irma.
- In "Donatello's Degree", Irma help Donatello to get his college degree pretending to be him; apparently the college believes that he's actually a woman called Donna Tello.
- In "Super Irma", Irma gets hit by a beam from a magnet, which made her think she had gained super powers. She then changes into a leotard, cape, and knee-high boots in an outfit in design similar to Wonder Woman.
- In fourth chapter of the Japanese manga of the Teenage Mutant Ninja Turtles, she's possessed by a magic katana for Shredder to destroy the turtles.
- And like April, Irma often plays the damsel in distress in many episodes.
- Many fans and pop culture bloggers have noted that Irma's look is quite similar to that of Jeanette of the Chipettes.
- Irma made a cameo appearance in the 2009 movie Turtles Forever. She is seen walking on a street when the Turtles appear in the 1987 dimension.
- Her family name Langinstein indicates a possible Jewish family background. Her dating Howie, a guy with similarities to Woody Allen, himself a Jewish comedian, can be interpereted as supporting this notion.
- Her original action figure bio states she isn't very smart.