He was voiced by the late Roddy McDowall.
Snowball is an orange hamster with tiny ears, a red nose, and pink skin on his paws, as well as matching pink eyes similar to Brain's and a stubby tail. His belly is slightly pudgy and while most of his fur is orange, his stomach is white. Just like Brain, Snowball has a big head that houses an equally big brain.
Initially, Snowball was an ordinary hamster and close friends with The Brain during their childhood. When the Gene Splicer malfunctioned with Snowball inside, although it made him highly intelligent, it also seemed to have a serious effect on his mind. From that point onward, Snowball's grip on reality grew weaker by the day, eventually making him deny his friendship with Brain, declaring him his enemy, and turning him into an vindictive, uncaring and aggressive hamster. Snowball is deceptive and manipulative, constantly telling lies so he can get what he wants. This is demonstrated by how he lies to Pinky and successfully convinces him that Brain uses him by stealing his brilliant ideas and calling them his own. Later on, in frustration, he reveals to Pinky that he was using him to get back at Brain for foiling his chain-letter scheme. He also appears to spy on his former friend to steal his schemes for world domination.
His main prominent character trait seems to be his strong hate for his former friend, The Brain, accompanied by his high intelligence that greatly matches Brain's and his intentions for world domination that highly differ from the latter's, as Snowball doesn't have good intentions and is willing to do all the immoral things Brain is not in order to take over the world. Brain's well-meaning is emphasized by his rivalry with the hamster, who proves to be far more cruel. Although Brain is disgusted by Snowball's methods and goes so far as to save the world from him, it is shown that, deep down, he still cares about his former friend to some degree as he's tried to save him even after their friendship had fallen apart, which also implies he's willing to give Snowball a second chance, only to be met with multiple betrayals. In "Welcome to the Jungle", when Brain rushes to Snowball to save him from a river, Snowball angrily refuses the mouse's help, indicating that he'd rather drown than let Brain help him, let alone rekindle their friendship. This further shows that Snowball truly does not have an iota of affection left for the mouse. Unfortunately for Brain, he can't say the same.
Although Snowball is a villain, he appears to lack any sense of good and evil when he appears as a normal hamster.
Brain and Snowball were very good friends while in their childhood, but when their genes were spliced, Snowball turned against Brain, and they became bitter enemies. He becomes head of the company MicroSponge and gets into frequent conflicts with Pinky and the Brain.
In the episode "Brainwashed Part 3- Wash Harder", Snowball is put back through the gene-splicer by his vengeful lawyers which reverses the effects of his genetic-splicing. He loses not only his intelligence, but also his anthropomorphism, reducing him to an ordinary hamster.
- In the spin-off, Snowball only appeared in episodes animated by Akom Film Production and Rough Draft Studios, Inc., the Korean studios. He never appeared in any episodes animated by the show's other animation studios, Wang and Tokyo Movie Shinsha Co., Ltd.; respectively (although the events of his debut episode are referenced in the Wang-animated episode "Brain Drained").
"Well, seeing that I've already stolen your chain letter scheme for world domination, how about your sidekick? A valuable asset?"
"Dung? Brain! Where are you?! You animal!"
"And if Brain said, 'eat dirt', would you do it?"
"Oh, don't be silly, Brain. It would take all the fun out of life; I derive my greatest pleasure from making you squirm."
"Psst! Pinky, Pinky, over here."
"Why haven't you picked up my mail yet?"
[about Pinky] "Eh, pathetic simpleton. He'll regret it."
"Anything I can take from you is an asset."
"Wink Martin-dale Day? Since when is there a...(pauses in realization) Brain. Brain! BRAIN!"
"So I've heard. Failing to take over the world must be very time consuming."
"Oh, don't worry Brain, you'll be joining him [Pinky] soon enough!"
"Pinky, The Brain doesn't care about you, he's just using you."
"Yes? Well, it's been a long time, my friend. You never call, you never write."
"Now if you'll pardon me, I have a world to conquer."
"Come on, come here. I've got fudge."
"Yes, using you! Stealing your brilliant ideas, calling them his own; he's using you!"
"You were always so darn dramatic!"
"A little. You should come and work for me, all the way The Brain treats you. Do you like it when he insults you? When he calls you names? When he bops you on the head?"