Snakeweed

Originally, the Kraang hired Snake—a small-time thug—to be a human go-between on missions that required a knowledge of Earth society.

During a battle between the Kraang and the Turtles, Snake was transformed into the mutant Snakeweed, a human/plant hybrid. Although the Turtles defeated him, Snakeweed continues to grow tougher in every battle, regenerating his poisonous, snaking limbs.