This is a MASSIVE series of characters from Flickr user soundofdesign (aka Ty Lettau) in the style of Mario's little (read: unpowered-up) form from the original Super Mario Bros. It...obviously took a long time to do. Way longer than it took me to name them all, which was like, 10 seconds. Ready? GO!
*panting* See? "You got the first one and most of the second one before trailing off and mumbling incoherently." Haha, you picked up on that, huh? You're a smart one.
Hit the jump for the rest including a ton of Star Wars, comic book, cartoon and every other character you could ever think of (except the one you're gonna complain about not being including in the comments!), plus -- PLUS -- OH GOD, what is this -- a bonus set of 139 characters as Mega Man, a third of which are WWF wrestlers. HAPPY F***ING DAY!!!!1 (be sure to check out the artist's Flickr page though to see them all in high-res and/or make one your new avatar).
Super Bros Pixel Art: 8-Bits or 16-Bits of Awesome? [technabob]
Thanks to Dane, who tried reversing things and drawing Mario in the the style of a Ninja Turtle but it just looked like Raphael holding a plunger.