Alvin Seville is one of The Chipmunks and the titular protagonist of the series and movies. He is the leader of the group as well as the self-proclaimed "awesomest" one. Alvin greatly relishes his role as band front man and his antics and ego regularly get him and his brothers (sometimes even Dave) into trouble.
Alvin, the shortest of the Chipmunk brothers, is always scheming, whether it be because he wants to get out of chores (Overworked Alvin) or is just trying to find a place to relax (Alvin's Cruise). Alvin has much musical talent; he not only sings, but also plays the harmonica. He loves his harmonica and will play it any time he can, even if it ends up messing up the song ("Alvin's Harmonica"). Alvin has trouble grasping other languages or their cultures but enjoys traveling the world anyway ("I Wish I Could Speak French", "Comin' Thru' the Rye").
He can be lazy when it comes to working, but he's very imaginative (Sir Alvin). He doesn't take lightly to people insulting him and his brothers' music (Squares), and sometimes even resorts to violence when dealing with people he dislikes (Daisy Bell in "Three Blind Mice"). He will also manipulate people when his fame is at stake (Disc Jockey). At times, the selfish side of Alvin can take over, but, in the end, he always returns to help his brothers and Dave (Alvin's Alter-Ego).
Alvin's interest in girls isn't as strong as in later incarnations, but he definitely is a charmer ("August Dear").
Alvin is the oldest, as revealed in the episode Grounded Chipmunk after making the statement, "I've never been alone, except those five minutes before Simon was born."
Alvin is charming, musical (able to play guitar, piano, and harmonica, among many others), and full of animal magnetism. He always seems to make up hare-brained schemes to accomplish whatever his goal at the time is; whether it be trying to help his brothers, keeping Dave from figuring something out, or getting out of a sticky situation. However, Simon seems to refer to his often illogical or crazy plans as challenging the ordinary.
Alvin has always possessed an impulsive behavior which has, at times, irritated or angered others around him, most obviously Dave. At times, Alvin's determination can be viewed as being thoughtless, greedy, or manipulative. As a result of his constant habit of reacting to opportunity, Alvin has gotten his brothers or himself in trouble quite a few times such as the balloon race in The Chipmunk Adventure and a large number of episodes.
Although Alvin is very much self-centered, he does care about his brothers. In Alvin and the Chipmunks Meet the Wolfman, Alvin helped Theodore temporarily get a bully off his case, causing the principal to remark, "I'll say this for Alvin: he sticks up for his little brother."
Alvin is an emotional roller coaster: his enthusiasm endless and despair bottomless. Alvin is often shown to be quite self-absorbed and greedy, but is also seen to be selfless and giving such as when he gives away his harmonica, one of his most prized possessions, to a child with a terminal illness in A Chipmunk Christmas. In A Chipmunk Reunion, Alvin has a difficult time forgiving his mother for leaving them until the end.
Alvin is commonly portrayed as the charming member of the trio. In the Dr. Simon and Mr. Heartthrob episode, he dresses stylishly and attempts to attract a group of visiting girls before being usurped by Simon, who drank a special kind of elixir which granted him natural magnetism and charm.
Alvin retains some of the traits he possessed from the 80s such as his impulsiveness, desire for fun, and charm as seen in Alvin and the Chipmunks: The Squeakquel where he manages to capture the attention of a group of girls using his cute looks and as well as the French language (e.g. he called BeccaMademoiselle after kissing her finger). Nevertheless, he has difficulty at showing affection toward Dave such as in the first film, Alvin and the Chipmunks, where he struggles at telling Dave that he loves him as a father, but less so with his brothers such as the time Alvin tried to kiss Simon to cheer him up in the second film. In the third film, when all of the Chipmunks are stranded on the island, Alvin slowly becomes the mature one, as seen when he yells at Simon (who had a change in personality due to getting bitten by a spider), only for Brittany to tell him he's starting to sound like Dave - much to his horror ("Nooooooooo!") and builds the boys' treehouse by himself.
Alvin contains much of his traditional personality: charming, impulsive, and self-centered. He continues to flirt with women such as Principal Meadows (Principal Interest) or have crushes and/or idolizations on famous individuals (Mister Manners). Though he acts in his self-interest, he recognizes when his schemes go too far and does what's necessary to make up to the one he hurt (To Serve And Protect). He's still protective of his brothers (Bully For You) and has familiar emotional attachment at times (Warbie). Alvin retains his sporty lifestyle of the 80s, frequently seen on his skateboard (What A Gem), though he tends to go too far when others are concerned (Mutiny).
Alvin's signature appearance has changed over the years. Before The Alvin Show, Alvin looked like a normal chipmunk somewhat similar to his CGI films appearance. Alvin wears just a red shirt with the letter 'A'. After The Alvin Show was created, Alvin was given more human features. His red shirt with his signature yellow 'A' is lengthen to go down to his new black shoes. Alvin was also given a red baseball cap and is the shortest of his brothers.
In Chipmunk Punk, Alvin wears clothes similar to The Alvin Show with the red sweater and matching hat. He also wears white and dark blue shoes and has a box cut instead of his regular hair as to match the visual style of the cover.
When the Alvin and the Chipmunks series was created, Alvin wore a red sweater with his signature yellow 'A' and a baseball cap. He also wore white and blue pattern shoes. In the early episodes, Alvin's eye color was black but, as the series progressed, his eye color changed to blue. In some episodes, Alvin wears light red footie pajamas with an 'A' on it, while in others, he wears a red t-shirt with a yellow 'A' on it along with red pajama pants.
In the CGI/live-action films, Alvin only wears a red hoodie with a yellow 'A' on it. His appearance was modified to look more closely to a real life chipmunk. He has brown hair as well as brown eyes. In the 2007 Alvin and the Chipmunks, Alvin is only seen wearing his cap twice; the first time on a magazine cover and the second at the end of the movie.
In ALVINNN!!! and The Chipmunks, Alvin wears a red and blue-hooded sweater with his signature yellow "A" on it, which also has a hole in the left sleeve (right in the promotional images), blue jeans, and red/orange/white converse shoes. Alvin regains his signature red baseball cap as a common accessory, but it now has green under the visor and orange on the top-visor. He has light orange-brownish fur and blue eyes. His pajamas consist of a t-shirt with a winged guitar illustration.
The relationship between Alvin and Dave is frustrating for the two of them at times. Frequently, Alvin will disobey which makes Dave scream his signature catchphrase "ALLLVIIINNNN!!!!", to which Alvin replies with a loud "OKAY!!" Although they can both irritate each other, they really love and care for each other.
In The Alvin Show, Alvin and Simon didn't usually argue or have a developing relationship until in the 1980's series. Generally, Alvin and Simon have a love/hate relationship. They get frustrated with one another, mainly because of their differences. However they eventually work things out. In Alvin and the Chipmunks Meet the Wolfman Alvin and Simon show a brotherly bond while working together to find a cure for Theodore. It is obvious Alvin cares for Simon, because in Bully For You, he wanted to help save Simon from Derek, the school bully. Despite Simon’s disagreements about Alvin’s plans, Alvin drags him into his schemes anyway.
Alvin's relationship with Theodore can sometimes be hard for Theodore. Sometimes Alvin enjoys teasing Theodore; it usually upsets Theodore, which Alvin doesn’t realize. Although Alvin is sometimes rude to Theodore, he cares and stands up for him as shown in Alvin and the Chipmunks Meet the Wolfman where he saved Theodore from Nathan, the school bully. Alvin also drags Theodore into his schemes.
Alvin and Brittany have a competitive relationship. They are constantly at odds with one another and argue, but they do show that deep down they love each other. They are shown in the future as married with twin boys.
Alvin and Jeanette are friends. She played Alvin's girlfriend in Chip Tracy, but they are actors in this episode. My Sister The Weirdo is one example in which Jeanette trusts in Alvin's abilities, such as his confidence, to help herself.
Alvin: That's it! I can't take this anymore. I can't! I give up! I'm sick of struggling for survival, competing with gophers and earthworms and that loser sparrow who always takes my nuts! And I'm especially sick of this stupid! Stupid! TREE!! - (Alvin and the Chipmunks)
Alvin: Dave likes to wear, dirty underwear, with little hairs! - (Alvin and the Chipmunks)
Alvin: Our parents were hippies. They left early to join a commune. - (Alvin and the Chipmunks)
Alvin: We're not performing monkeys, Dave! Why do we have to sing for that guy anyway? - (Alvin and the Chipmunks)
Alvin: That hurts, Dave. That really hurts. - (Alvin and the Chipmunks)
Alvin: You should have kissed her, Dave! She wanted you! - (Alvin and the Chipmunks)
Alvin: MAJOR ROCK STARS. - (Alvin and the Chipmunks)
Alvin: You'll never take us alive!!! - (Alvin and the Chipmunks)
Alvin:You talking to me? You talking to me? I'm the only one here, so, you must be talking to me! - (The Squeakquel)
Alvin: Oh, relax. It's like Ryan says, who's going to beat singing chipmunks? - (The Squeakquel)
Alvin: I never thought I'd say this, but...pink is my new favorite color. - (The Squeakquel)
Alvin: Got it. Straight to the top. Ironic. - (The Squeakquel)
Alvin: I will create a spark by striking this rock with my Swiss army knife...which Dave took from me. - (Chipwrecked)
Alvin: Okay, this is crazy. Building a shelter was your idea! Yours!!! - (Chipwrecked)
Alvin: Hey, guys! Look what I won! Isn't he cute? Look at that face! - (The Road Chip)
Alvin: Ah, I see your problem. It's obvious. This has been written by aliens. - (Un-Send!)
Alvin: I can't let you get hurt Jeanette. My reputation isn't worth it. - (Wacky Wednesday)
Even though Alvin is the oldest by five minutes (as stated in the 80s episode Grounded Chipmunk), many fans believe that he is younger than Simon since Simon is taller and more mentally mature.
Alvin's age is unknown in the CGI/live-action films.
In the CGI/live-action films, Alvin has only worn his baseball cap in the 2007 movie (in a magazine and at the end).
In the CGI/live-action films, Alvin is also depicted as having the ability to speak basic French unlike in both the 1980's animated series and The Alvin Show in which he is shown to be unable to speak French in "Petit Papa Noel" from A Very Merry Chipmunk, and he is shown to wish he could speak French in The Alvin Show musical segment "I Wish I Could Speak French."
According to Romancing Miss Stone, Alvin says that his birthday is nearby and he is turning nine years old (along with his brothers). However, later on in the series, they are stated to be eight years old several times.
Alvin's attire has changed many times throughout the franchise with him wearing the most clothes in the new CGI series and him wearing the least amount of clothes in the live action/CGI films.
During the 2000-era, Alvin was, and is, known as the self-appointed "leader" of the group. And, presumably meaning The Alvin Show, he suffered from small "munk" complex and tried to make up for it with his grand schemes and animal magnetism.
In the CGI/live-action films, Alvin is shown to have great hands when catching: in The Squeakquel (when he joins the football team and makes a game-winning touchdown catch), Chipwrecked (he catches a pocket knife with one hand in mid-air), and The Road Chip (he catches a ring with one hand in mid-air, with a fully-extended body).