Rats. At first glace, I can only identify ten or eleven of them. I am in the mood for a bit of Bubble Bobble now though, and that's not a bad thing.

Am I really the first guy to try? Ok, here goes:

A=ToeJam from "ToeJam and Earl"
B=Bob/Bubblun from "Bubble Bobble"
C=Revenent from "Doom II"
D=Yoshi from "Super Mario World"
E=Yellow Comet's Medium (Main Battle) Tank from "Advance Wars"
F=Spider-Man from "Marvel Super Heroes: War of the Gems"
G=Ken from "Street Fighter II"
H=Gosh, I wish I knew because he looks really cool!
I=A very freudian monster from I don't know where.
J=I wan't to say Karate Champ, but probably not.
K=No idea.
L=A giraffe. From the planet Earth.
M=Ooh, I can ALMOST remeber this one. Darn :(
N=A POW from the "Metal slug" series.
O=Voltorb from "Pokemon."
P=No clue.
Q=Alucard from "Castlevania: Symphony of the Night."
R=Bruce Campbell?
S=Huh, I didn't realize that "Birdy the Mighty" got a video game :P
T=Kinda tough to tell without being able to see his face. I'm gonna guess that he's from something SNK-related. But I doubt it's KoF.
U=A cockroach. *shrug*
V=He seems like a Castlevania enemy, but not one I've ever seen before. I did miss some games, so...
W=Huitzil/Phobos. First playable in "Night Warriors: Darkstalkers' Revenge."
X=No idea.
Y=Total Gym?
Z=Homer Simpson from "The Simpsons Arcade Game."

That image really makes me wanna go track down a copy of Bust-A-Move for my old Super Nintendo. I loved that game so damn much.

ha ha! I see some Metal Gear Solid GBC up there! Loved that game so much.

except that box puzzle, it can rot in hell.

Wait, now that I realize these are supposed to be letters, is that M for Metal Gear, or G for Gander?

1. Toejam from Toejam & Earl
2. Character from Bust-a-move/Bubble Bobble
3. First thought was Doom, but the aesthetics don't look quite right
4. Yoshi from Super Mario World
5. I know it's from Advance Wars, dunno the unit name
6. Spider Man from the Marvel fighting and Marvel VS series
7. Ken from Street Fighter 2
8. Obviously Metal Gear, but I'm not familiar with the handheld or MSX games
9. Some kinda phallic alien?
10. Karate Champ I think
11. Playable character from MC' Kids
12. No idea, but my brain screams Earthbound/Mother 2
13. The name is lost to me, but I'm pretty sure its a classic schmup from the arcade/nes era
14. P.O.W from Metal Slug
15. Voltorb from Pokemon
16. No idea at all
17. Alucard from Symphony of the Night
18-19. No idea at all
20. Definitely from an SNK fighter, no idea who it is though
21. Filthy Roach enemy from Mother 3
22. No idea, but he looks like a mix of shaft from Symphony of the Night, and Agahnim from A Link to the Past
23. Phobos/Huitzil from Darkstalkers
24-25. No idea
26. Homer Simpson from the arcade game

Well that was fun, only recognized about 50-60% of them though.

@Neo K is Karate Champ and I is from Splatterhouse.

Ill try fill in some of the blanks from NeoshinGundam -

H - Snatcher???
K - McKids
M - Xevious
R - Adventures of Rad Gravity

@ phr33kachu, good spot with splatterhouse, as for karate champ i dont think that sprite is from karate champ.

Yeah, no idea with this, but stuff like this would be cool to have on the site.

I'm sad that nobody recognizes the original Duke Nukem anymore. I'm old. :(

NO SPOILERS IN THE COMMENTS GAWD

I guessed 11 of them. I'm fairly confident that I got all those correct.

Throwing in the Metal Gear form Ghost Babel was a nice touch.

I think the red phallic monster is from Marathon.

P = Asha from Monster World IV
Y = Duke Nukem from Duke Nukem (as Webrat pointed out)

SPOILERS BELOW

Here's my attempt, compare yourself to me and feel better, man.

1) Toejam from Toejam and Earl
2) Bubble Bobble dinosaur
3) Something from Killer Instinct?
4) Yoshi from Super Mario World?
5) Heavy Tank from Advance Wars
6) Spiderman from a game I never played, probably.
7) Ken, doing a shoryuken from some version of Street Fighter 2
8) A purple cobra mech thing.
9) Pikachu :)
10) Karate man
11) The black kid from that McDonald's videogame?
12) Giraffe.
13) No idea.
14) Prisoner of War from Metal Slug.
15) Voltorb from Pokemon
16) Selena from The Legend of Lufia?
17) Uhhh.
18) Even more uhhh.
19) Streets of Rage person?
20) Fighting game character man
21) A cockroach enemy (name?) from Earthbound
22) The Count of Monte Cristo
23) A perpetual motion device.
24) Redbeard the Sprite
25) Johnny Claw
26) Homer Simpson

#18 is Rad Gravity from The Adventures of Rad Gravity. Now that's a pretty obscure NES game.

I was able to get most of these. That's an awesome collection of alphabetized game characters!

For everyone trying to guess T, he's Rugal Bernstein, from The King of Fighters, maybe '97 or '98

No one recognized Zemus?!?! Comon, FF4 is one of the finest games ever made :(

Yeah, 22) is Zemus.

@Raby

I was gonna say the same thing about everyone who mis-identified the Doom II Revenant and GD Duke Nukem!

A) Toejam - Toejam and Earl
B) Bub - Bubble Bobble
C) Revenant - Doom 2
D) Yoshi - Super Mario World
E) Tank - Advance Wars
F) Spiderman - Marvel Super Heroes
G) Ken - Street Fighter 2
H) Metal Gear Gander - Metal Gear: Ghost Babel
I) Giant Boreworm - Splatterhouse 3
J) Player 1 - Karate Champ (this one doesn't feel right)
K) Mack - M.C. Kids
L) Giraffe - Bible Stories (probably wrong)
M) Want to say enemy from Xevious but i don't think it's right.
N) P.O.W - Metal Slug.
O) Voltorb - Pokemon
P) Christ, that looks familiar.
Q) Alucard - Castlevania: Symphony of the Night
R) Rad Gravity - The Adventures of Rad Gravity (I loved that game.)
S) Carol - Captain Commando
T) Rugal Bernstien - King of Fighters (looks like '98)
U) Cockroach - I'm guessing Earthbound
V) Zemus - Final Fantasy 4
W) Huitzil/Phobos - Darkstalkers
X) No clue
Y) EGA Duke Nukem - Duke Nukem
Z) Homer Simpson - The Simpsons Arcade Game

That's pretty comprehensive.

Here's my list, which I came up with before looking at any of the comments, but I noticed one thing scrolling my way down here - that's not a Voltorb, it's an Electrode. Anyway.

1) Toejam (Toejam & Earl)
2) Bub (Bubble Bobble)
3) Revenant (Doom or Doom II, I forget where he showed up first)
4) Yoshi (Super Mario World)
5) Main Tank (Yellow Comet) (Advance Wars)
6) Spiderman (believe that's his MvC or MvC2 sprite)
7) Ken Masters (Street Fighter II)
8) it's the Metal Gear from that GBC MGS, can't remember the name
9) Boreworm? (Splatterhouse, either 2 or 3)
10) White/Player 1 (Karate Champ)
11) Mack (M.C. Kids)
12) Giraffe (Zookeeper?)
13) Looks like something out of Xevious, Sinistar, or something similar, but I can't pin it down
14) POW (Metal Slug series)
15) Electrode (Pokemon)
16) This one's killing me, I swear I've seen that exposition/helper fairy somewhere
17) Alucard (Castlevania: SotN)
18) Rad Gravity (Adventures of Rad Gravity)
19) Carol (Captain Commando)
20) Rugal (KoF)
21) Filthy Attack Roach (Earthbound)
22) Zemus (FFIV)
23) Huitzil (Darkstalkers)
24) Cid from Final Fantasy III (NES, not the one that was actually VI), maybe? I dunno.
25) Duke Nukem (Duke Nukem, pre-3D)
26) Homer Simpson (The Simpsons)