Neff (Altered Beast)
Younger players will see a purple rhinoceros and figure, sure, a purple rhino, why the hell not, video games have all sorts of crazy crap in them nowadays. Veterans will recognize the character as Altered Beast's shapeshifting antagonist, the demon god Neff, who's apparently let himself go in the years since anyone last played that game to completion; he's seen here finally taking a break from Welcoming You To Your Doom in order to Welcome Ralph To The Free Coffee-Tray.
Cyril the Zombie (House of the Dead)
Zombies is zombies is zombies, right? Not so! If you can name every game where you're attacked by an axe-wielding, male-pattern-balding undead, please go right ahead and do so and we'll get this reference sorted out; otherwise, we'll save you some time and say that the character's specific inspiration is House of the Dead's axe-wielding, male-pattern-balding Cyril.
And if you're looking for more gaming goodness, check out every game reference in Scott Pilgrim and gaming innovations that weren't as cool as we thought they'd be.