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:
OpenGameArt.org can automatically generate a single credits file for all of the art in this collection. Please note that, while we tried our best, this file is in no way guaranteed to be accurate, and properly attributing the work you distribute with your project remains your responsibility. You'll want to load up this file in a text editor, check to make sure everything looks good (and that any special attribution instructions are followed), and then delete the notice at the top of the file, as the notice is designed to make you look very silly if you don't check over the file and remove it.