List of cameos in Wreck-It Ralph

Focused around video game characters, Wreck-It Ralph features numerous video game characters from multiple publishing companies alongside the film's cast of original characters, much like the 1988 film Who Framed Roger Rabbit.

Disney

 * Tiny the T.Rex from Meet the Robinsons (Appearing in Game Central Station as a Generic video game Dinosaur.)
 * One of the game portals in Game Central Station reads "TRON".

Disney Interactive Studios

 * Sora from Kingdom Hearts (In the Tapper scene, you can see an 8-Bit version of him in his Kingdom Hearts attire at the bottom-left corner of Tapper.)

Nintendo
(Note: Mario and Luigi, the protagonists of Super Mario Bros. were intended to have appeared in the film, voiced by Charles Martinet. However, the producers couldn't find a place to work them into the story, that felt right for their significance, along with paying a hefty licensing fee. However, Mario is mentioned by Fix-It Felix in the film.)
 * Bowser (King Koopa) from Super Mario Bros.
 * A Super Mushroom from Super Mario Bros.
 * Princess Daisy from Super Mario Bros.
 * Rosalina (Rosetta) from Super Mario Galaxy

Sega

 * Sonic the Hedgehog from Sonic the Hedgehog
 * Miles "Tails" Prower from Sonic the Hedgehog (Picture on a wall in Tapper's Bar.)
 * Dr. Robotnik (Eggman) from Sonic the Hedgehog
 * Neff from Altered Beast
 * Cyril the Zombie from House of the Dead
 * AiAi from Super Monkey Ball
 * Cyborg from Cyborg Justice
 * Mishaela from Shining Force

Capcom

 * M. Bison (Vega) from Street Fighter II
 * Zangief from Street Fighter II
 * Chun-Li from Street Fighter II
 * Cammy from Super Street Fighter II
 * Ken from Street Fighter
 * Ryu from Street Fighter
 * Blanka from Street Fighter II
 * Beholder from Eye of the Beholder
 * The car-breaking bonus stage round from Street Fighter II
 * Sheng Long from the Street Fighter series (his name appears as a graffiti at the portal leading to Sugar Rush).

(Note: Dr. Wily from Mega Man was originally set to make an appearance in the Bad-Anon villains support group as seen in an early render, however he was cut in the final version of the film.)

Midway

 * Kano from Mortal Kombat
 * Smoke from Mortal Kombat
 * Paperboy from Paperboy
 * Bartender from Tapper
 * Sauron from Primal Rage

Namco

 * Clyde from Pac-Man
 * Pac-Man from Pac-Man
 * Inky Ghost Monster from Pac-Man
 * Blinky Ghost Monster from Pac-Man
 * Pinky Ghost Monster from Pac-Man
 * Dig Dug from Dig Dug
 * A Pooka from Dig Dug
 * A Fygar from Dig Dug

Gottlieb

 * Q*bert from Q*bert
 * Coily from Q*bert
 * Slick from Q*bert
 * Ugg from Q*bert
 * Sam from Q*bert

Square Enix

 * Aerith from Final Fantasy VII (Refrenced and written in graffiti as Aerith Lives on a subway wall in Game Central Station.)
 * Lara Croft (Used by Wreck-it Ralph as a false name when trying to get past security.)

Konami

 * Frogger from Frogger
 * Yuni from Dance Dance Revolution
 * An Exclamation mark (!) from Metal Gear

Atari

 * Paddle 1 and Paddle 2 from Pong
 * A racer from RoadBlasters

Taito

 * An Alien Invader from Space Invaders (on a picture)
 * The Qix from Qix

Data East

 * Peter Pepper from BurgerTime

Williams Electronics

 * Knight and Ostrich from Joust

Blizzard North

 * Diablo from Diablo (referred as "Satine")
 * Leroy Jenkins (Shown as Graffitti on the Terminal Wall of "Jenkins")