Tobin "Toby" Seville is Dave's immature and lazy cousin and the Chipmunks' other caretaker. He is a slacker, who loves to play video games. He is played by Zachary Levi.
He also lives with Aunt Jackie and he referes to himself as the Tobster.
In the events in the second film Dave is seriously injured in a benefit concert as a result of Alvin being carried away and knocking a giant statue into Dave, sending him flying a good distance. Dave survives the accident but is left temporarily disabled as the result. During his recovery Dave reveals that he has arranged for them to go to school and for Toby to watch after him during his recovery. When Toby arrives to take care of the chipmmunks he is depicted as being lazy and having a love for video games as well as having a sarcastic demeanor. It is hinted through movie clips that Toby is having trouble controlling them and is often quarraling with the chipmunk trio as an example while playing a video game Alvin breaks Daves new T.V and a nervous Alvin suggests they play his second favorite game which is to hide the broken TV much to the shock and disbelief of a stunned Toby also he is referred as "Taco boy" by Simon and when Toby claimed as being extremely popular when he went to school he is countered by the disbieliving chipmunks who point out that he is still living with his mother, refers to himself as the Tobster and constantly going "pew, pew pew". A slightly amused Toby responds by giggling sarcastically and sending them off to bed early. It has also been revealed that Theodore is constantly trying to bond with his temporary guardian but after failing runs away from home.
Later on, Toby, Alvin and Simon find Theodore at the L.A. Zoo. Theodore escapes from being eaten by an eagle. Near the climax of the movie, Toby is able to stall Alvin's income to bring the Chipettes to the Music Festival by singing to his crush with a few lines. Despite not singing much, the audience critically accept what he says into the microphone and Alvin managed to get in time with the helicopter and the Chipettes after Toby's unplanned talent.
- He was tormented by bullies when he was a teenager at the same school the Chipmunks go to in the Squeakquel. He had his face dumped into the toilet and was pinched by people because of a paper that said "Pinch Me" taped to the back of his shirt which he didn't notice.
He broke half of the band/music program's instruments and he ran but when he went on stage at the end of the movie Dr.Rubin never sued or lectured him.