I've been looking around the only overworld-character sprites I can find are from the character creation menus, which not all characters have. Specifically, I'm looking for Roman Apollo v1's character sprites. Where should I be looking? Is there anywhere where I can find an image of just the sprite, with no BG?
Have you checked the resource pack, it includes many talk sprites with no background. If you're looking for Apollo's tiny sprite (walk sprite), it's in there as well, but you will need something that opens adobe illustrator files.