His name is never revealed in the 2003 cartoon; rather, it is the from the first issue of the Dreamwave comic, where a little more background on his character is explored.
You're going down, freaks! Nobody messes with the Purple Dragons! Especially wearing stupid turtle costumes!
In the actual episode content itself, one evening John leads the Purple Dragons in using an armored car to steal a large amount of money. The Turtles, who were, driven by certain adverse circumstances a few minutes ago from their underground home to the surface, accidentally came upon John's group. Raphael hide in the armored car to avoid their grasp. However, Raphael inadvertently gets trapped in the vehicle, prompting the Turtles to chase after them.
After catching up to them, the other Turtles freed Raph, and Johnny and his men found the Turtles and cornered them. The Purple Dragons are soundly defeated by the Turtles, making the thugs run away. Johnny personally reported his failure to Oroku Saki. He promised Saki that he won't fail him again. Despite pleading for his life (and incorrectly referring to the Turtles as "karate frog creatures", despite initially identifying their species correctly), he is apparently killed by an irate Oroku Saki.
He was later replaced by Dragon Face as acting leader of the Purple Dragons.
- John was voiced by Eric Stuart, the same person who voiced Harry Parker.
- Johnny was one of the few 2003 TMNT series characters to be killed, albeit offscreen.
- In the season 4 episode "Dragon's Brew", a recycled voice clip of John's "Let's get out of here!" from "Things Change" is used for the voice of a Purple Dragon running away.