Mohawk is a member of the Purple Dragons and through this association, an enemy of the Ninja Turtles. This character was created specifically for the 2003 animated series.
History
Mohawk is a Purple Dragon member with a tall pink mohawk haircut, who appears in TMNT: Back to the Sewer. He appeared in several adventures of the Turtles' as a lesser antagonist. His name is mentioned in the episode City Under Siege.
Turtles Forever
In Turtles Forever he is with some other Purple Dragons members who caught the Turtles from the Fred Wolf reality. When the 4 Kids Turtles liberated their Fred Wolf counterparts, he was splashed with Mutagen - and because he had been in contact with a fighting dog of the Dragons which he was holding on it's leash - he was turned into a dog mutant. In his mutated form he helped Hun attack, the two groups of Turtles and the 03- Splinter. The latter which fired missiles at Mohawk with the Battle Shell, which shredded him.
Later at the Purple Dragon Headquarters, Mohawk was somehow still alive and returned back to his normal state and fought alongside a mutated Hun against the Turtles and was last seen getting erased from reality due to the Utrom Shredder's plan.