Ron's pet naked mole rat. Ron and Rufus are inseparable, and Rufus can almost always be found riding in Ron's pocket. Rufus has similar interests and personality traits as Ron (such as a love of Bueno Nacho and video games), to the point that he often mimics Ron's actions, emotions, and facial expressions. Despite being a rodent, Rufus is actually very competent and level-headed, and often comes to the rescue of Kim and Ron when they're in a pinch. He has very good technical skills, and Ron often uses him to fix broken appliances. He also has extremely strong teeth, and can even chew through some metals. He's even an accomplished martial artist, and has Monkey Kung Fu powers, like Ron; in fact, he can control them even better than him.
Rufus is the only animal on the show to display characteristics of anthropomorphism and sapience. Much like Scooby-Doo, Rufus is marginally capable of human speech (able to utter a couple of words), but mostly talks in high-pitched rodent jabber. Only Ron (and, to an extent, Kim) actually seems to understand him when he speaks (apparently, Ron has the ability to communicate with animals, but is somewhat impaired by the fact he's afraid of most of them).
Rufus is often used as a deus ex machina when the characters are in trouble.
Rufus is Ron's pet because when Ron was 12, his parents told him he could have only a hairless pet because of his Dad's allergies, so Ron purchased Rufus at Smarty Mart. Ron chose to name him Rufus after an imaginary friend he had in pre-school.
In a crossover episode of Lilo & Stitch: the Series, Dr. Jumba Jookiba mistook Rufus for Experiment 607, but Stitch revealed that Rufus was indeed a naked mole rat.
Rufus even has his own theme song ("The Naked Mole Rap"), although Kim herself does not. (As Ron pointed out in "Team Impossible".)
Rufus is voiced by Nancy Cartwright.
From: brook
i love the naked mole rat