Alvin Seville: The leader of the Chipmunks and middle brother, Alvin is the talented "troublemaker" of the group.
Simon Seville: The oldest brother, Simon is the intelligent realist and the most responsible of the group.
Theodore Seville: The youngest brother, Theodore is the cute innocent butterball of the group.
Brittany Miller: Brittany, the leader of the Chipettes, is Alvin's counterpart. She is as equally vain and self-centered as Alvin. But like him, she really does care about others.
Jeanette Miller: Jeanette is Simon's counterpart. However, unlike Simon, who stands up to Alvin easily, she does not stand up to Brittany as easily. She is also very smart, which is what she does have in common with Simon. However, she is very shy and clumsy.
Eleanor Miller: Eleanor is Theodore's counterpart. She shares his love for food and cooking. But she is more athletic, more intelligent, and more likely to stand up to Brittany than Theodore is to Alvin.
David "Dave" Seville: Originally The Chipmunks' first adoptive father, songwriter and manager, Dave's patience is tested nearly every day by Alvin, usually to the point where he yells "ALVIN!!!". Despite this, he loves all of the boys equally.
Miss Beatrice Miller: The kindly, absent-minded adoptive mother of the Chipettes. She occasionally babysits the Chipmunks and has a crush on Dave, even though she's old enough to be his mother. In her youth, she was part of an all-girl singing group called "The Thrillers".
Lilly: The Chipmunks' Rossini puppy who they adopted from the shelter following the death of their original pet, a kitten named Cookie Chomper III.
Vinny: The Chipmunks' birth mother (originally voiced by June Foray, then by Janice Karman). The Chipmunks find their long-lost mother after days of searching. Alvin gets upset because he doesn't understand why she abandoned them. Their mother explains that the year she abandoned them there was a horrible winter and all of the animals in the forest were forced to leave their homes. She realized that they wouldn't survive the journey if she brought them with her, so she decided to leave them with a nice man who was always kind to the forest animals (Dave). She told them that when spring came and she could finally return to get them, she saw how happy they were with Dave, and thought they would be better off with him. Eventually, Alvin forgives his mother. They return to Dave, but the brothers agree to keep in touch with their mother. In a later episode she and Dave clash on how to bring the boys up. Eventually they make up.
Plus Many More!