Continued with my knowledge and some other things posted. The obnoxious ?????s are so that when people skim through this, the know people are still unidentified even though they have things written in their places.
H: Han Solo
He: Heavy
Li: Link
Be:
B: Bomberman
C: Cloud Strife
N: Nova
O: looks familiar... ?????
F: Fox McCloud
Ne:
Na: Naruto
Mg: Mega Man
Al: Alice (I think ?????)
Si: The Sims
P: Pac-Man
S: Samus
Cl: Clank
Ar: The Arbiter
K: Kirby
Ca: CATS
Sc: Sonic
Ti: Also looks familiar ?????
V: Vectorman
Cr: Crash Bandicoot
Mn: Manny Calavera
Fe: Marcus Fenix
Co: King of All Cosmos
Ni: NiGHTS
Cu: Cutman
Zn: Zangief
Ga: Ganondorf
Ge: Gex
As: Astro Boy
Se:
Br: Blood Rayne
Kr: Kratos
Rb: R.O.B.
Sr: Sephiroth
Y: I don't think it's Yanma, but interesting guess(?????)
Zr: Zerg
Nb: Niko Bellic
Mo: Mario
Tc: T.C. Combo
Ru: Rush
Rh: Ryu Hayabusa
Pd: Uhhh... someone from Perfect dark????? no idea, just a random guess
Ag: Agent 47
Cd: I think it's Dracula, or possibly another Castlevania vampire ?????
In: Indiana Jones
Sn: Solid Snake
Sb: Strong Bad
Te: Toejam and Earl
I: Kid Icarus
Xe: Xemnas
Cs: Carmen Sandiego
Ba: Batman
La: Lara Croft
Ce:
Pr: Princess Peach
Nd:
Pm: Pikmin
Sm: Sam and Max
Eu: Eugene Krabs
Gd:
Tb: The boy, from A Boy and his Blob
Dy: Dr. Wily
Ho:
Er: Earthworm Jim
Tm:
Yb: Yogi Bear
Lu: Luigi
Hf: Heefer
Ta: Tank
W: Worm, from Worms (Worms 3D, or one of the 3D games anyway)
Re: Ronin (this guy has a full name but I forget it he's from UT3)
Os: Again, looks familiar ?????
Ir: Ironman
Pt: Pitfall
Au: Auron
Hg: Hagar, from Final Fight (????? for sure, but I'm about 75% sure)
Tl: Tails Prower
Pb: Pinky and Blinky
Bi: Birdo
Po: Popeye
At: Afro Thunder
Rn: Raiden
Fr: Gordon Freeman
Ra: Rash
Ac:
Th:
Pa: PaRappa
U:
Np:
Pu: Pikachu
Am: Amigo
Cm: Cooking Mama
Bk: Bowser
Cf:
Es: probably from the same game as "Os" ?????
Fm: Fireman
Md: John Madden
No: Noob Saibot
Lr: Larry
Rf: Raphael
Db: Diablo
Sg: Sagat
Bh: Hammer Brother
Hs: Homer Simpson
Mt: Mike Tyson
Ds: Dr. Stewart
Rg:
Uub: guy from Doom ?????
Uuq:
Alright, we're getting close, I think we'll be able to do it without looking up a list or anything.