Simon Seville is the smartest of the group, possessing an I.Q. just north of Einstein. He is the only original chipmunk in the series known to be bespectacled. He possesses a very dry sense of humor as well as a keen wit. Simon gets along great with Jeanette, one of the The Chipettes, who is smart, just like him. They are shy about their relationship, however it is obvious that he cares for her.
Simon's age role has changed over various generations. In the 60's cartoons, he was the oldest of his brothers, while in the 80's cartoons he was the middle child, as revealed in the episode Grounded Chipmunk when Alvin states he has never been alone, except those five minutes before Simon was born. In the CGI films his age is unknown.
Alvin exploits Simon's master mind. In the end, Simon loves Alvin, although he secretly worries that they share the same gene pool. His signature color is blue, and has the same color eyes. He wears black glasses in the live action film. His instrument is the bass guitar. In the 2009 sequel , he was convinced he was given a swirlie by some jocks. After he and Alvin saw them picking on Theodore, he and Alvin attacked the bullies. Later, he is tricked into thinking that he is the school's litter monitor, only to find it was a joke. Simon has a crush on Jeanette. He holds to be the middle aged chipmunk, although he is taller and more mature than Alvin. He cares deeply for Theodore and Alvin and their well being, but wishes Alvin would act more mature and stand to learn more. He relishes Theodore's good nature but Alvin always takes to taking advantage of Theodore's gullibleness along with the fact that he is young and naive. He cares for Alvin even though they always fight, but he worries if somewhere deep down, they are alike.
In Alvin and the Chipmunks: Chipwrecked, Simon has an alternate personality caused by a spider bite. His alternate identity goes by the name Simone and speaks with a French accent. Simone is depicted to be braver than Simon and also is less uptight than Simon. Near the end of the movie Simon recovers from the bite and reverts back to his usual personality.
Just like Alvin although Simon's appearance may change, he will always stick to wearing a dark blue top and a pair of glasses, before the Alvin Show mostly in the Dave Seville and the Chipmunks albums Simon wears an red vest with an S on it, in the Chipmunk song album Simon wears red pajamas similar to the ones his brothers wear while he has a white S standing for his name on the red pajamas while dancing around a Christmas tree. When the Alvin Show was created Simon just like Alvin and Theodore was given more human features, instead of a red vest Simon now wears a blue sweater that goes all the way down to his shoes, he wears a pair of black glasses with white lenses and all black shoes.
In Chipmunk Punk Simon's hair is spiky as if he were a rock star, he once again wears his black glasses, blue sweater and all black shoes.
In The Alvin and the Chipmunks Series Simon wears black glasses with white lenses, a blue sweater, he also wears a pair of white and red patterned shoes. As the series progresses Simon's sweater becomes darker and his glasses become blue, then during the near end and Chipmunks Go to the Movies his glasses are purple.
Since 2007 Simon only wears a blue hoodie and a pair of glasses that came from a toy Santa Claus, his appearance was modified to look more closely to a real life chipmunk.
Simon and Dave have a close relationship, because Dave takes care of the Chipmunks and Chipettes like they are his kids. Simon loves Dave and Dave loves Simon.
Simon and Alvin always seem to be fighting. Alvin always does something to make Simon mad. But, Simon is protective of Alvin and loves him.
Simon and Theodore also have a really close relationship. Simon always seems to be with Theodore most of the time. Simon is also protective of Theodore and Simon loves him as much as he loves Dave and Alvin..
It is really obvious that Simon loves Jeanette. Jeanette loves Simon back. He shows his true love for her through Simone and when they are on their raft, waiting for a rescue helicopter. He tells Jeanette that even the most perfect gem can not compare to her beauty. Jeanette smiles and so does Simon.
Simon and Brittany never show a romantic relationship. They also don't show a friendship. But Simon always looks after Brittany, though.
Simon and Eleanor don't love each other, but they are friends and they care about each other. Simon looks after Eleanor, like he looks after Brittany, Alvin, Theodore and Jeanette.
Simon and Ryan are not friends. Even though Ryan is friends with Alvin, he still bullies Simon and Theodore. Simon is really strict with Ryan.
- The origin of his name comes from Simon Waronker.