Platformer/Sidescroller Characters and Enemies
This is a stylistically general, complete collection of platformer characters, enemies and vehicles on OGA. I've been through the entire archive and I keep it up to date day to day, but if you see anything I've missed please drop a line in the comments.
NOTE: I also maintain a collection of sidescroller/platformer tiles, which might also be of interest:
as well as a collection of platformer items and effects: