These are the four main characters I made for Doomed Looters - a small 2d action roguelike game and my entry for 2016 edition of 7DRL competition.
I think, despite their defects, they're nice enough, and they fit well in this kind of game (at least for prototyping).

Each spritesheet has 2 idle frame, 2 walking frame, 3 attacking frame, for down, up and right direction - directions are in different rows (I used right even for left, just flipping it, even if it's not exactly correct).
Sprites are 32x32 pixels.

I release them with CC BY 3.0 licence that means you can use them freely, even for commercial purposes, and you can adapt them if you need it.
Only requested things is to credit me:
Marco Giorgini - http://www.marcogiorgini.com

I hope they can help you in some of your projects. If so, and if you want, drop me a line telling me about your game.

P.S. if you want to see these characters in action you can check game page - where if'll find also a video.