These are the fictionalized villains who are green.
Plankton (SpongeBob Squarepants)
Dr. Doom (Marvel Universe)
Sigma (Mega Man X series)
Reptile (Mortal Kombat series)
Vicky the Babysitter (The Fairly OddParents)
Chip Hazard (Small Soldiers)
The Grinch (Dr. Seuss franchise)
Peter Griffin (Family Guy)