These aren't awful. Some suggestions.
With the Pyro one. His arms are much more thin in your sprite than they are in-game. His neck is also covered by the gas mask, not the suit. The boots are fine (except for that "stray" pixel on the right (Pyro's right) boot). His legs should also be slightly thicker, and the uh... "baggage" (I seriously have no better way of putting this) below his belt should be... more. More baggage, there you go. Also those straps are for suspenders, not a backpack. They should connect to the belt, not go around his torso. Speaking of the torso, it's all sorts of fucked up. I really don't even know where to begin with it. Honestly my only suggestion would be to redo it and actually make it look more "natural". The gloves aren't bad but the lack of thumbs is bothering me. Lastly, the shading is different for the legs and torso. The legs are fine because you have an actual light source going there (the flame), but the torso's is awful (gradient shading is never the way to go; GG2's Pyro is awful, don't base your shading on it). Really, I can't say much more than clean up that first sprite, and then maybe I could tell you what to improve on after that.
The elf Runner picture. I'm not gonna critique the Runner because it's a really simple edit, even though it falls under what I'm going to critique here. There is a lot of bitmixing in that picture. Bitmixing is a term that when used here, means that some pixels are different sizes than others in the same sprite. Basically, you have every pixel be a certain size, but then make certain pixels smaller than others. Maybe what you did is resized the image, then added smaller pixels to various areas. Either way, don't do it because it's really ugly. Make all your pixels the same sizes.