Jeanette Miller is the second of The Chipettes, younger than Brittany and older than Eleanor. Her last name is Miller in the 80's cartoon, but she does not have a stated last name in CGI. It is presumed to be Seville because of The Chipettes being adopted by Dave.
Jeanette can best be described as the "absent-minded professor" of the group. Gifted with extraordinary intelligence, she often is so caught up in contemplating the universe that she forgets the simple matters of life, such as not tripping over her own feet. She can generally be found with her shoelaces untied, one knee sock wrinkled around her ankle, and her buttons askew. She is actually more like Theodore than Simon in a sense, as they are both sweet, timid, and shy, but her interests and talents are closer to Simon's. Jeanette has very poor vision, and is virtually helpless without her glasses. She is also very clumsy, and tends to knock into things often. She has brown hair and green eyes, and her signature color is purple. In the series, she has black glasses in the first season and Alvin and the Chipmunks Meet the Wolfman, and pink glasses in the second season to the final season and specials. Jeanette gets along well with Simon of The Chipmunks. However, they are very shy of their relationship.
Though her CGI version retains many of the traits she had in the cartoon, there are some notable differences. She has an insecure personality, regularly saying “I'm not good with things like this.” However, she eventually learned to be brave and take more risks, though still being cautious. She is also slightly more outspoken, sometimes surprising even her sisters. Though this may be seen in the third movie, she is not shown to be very clumsy at all; when dancing and performing, she can actually keep up well with her sisters and The Chipmunks, never faltering or stumbling. In the films, she has violet eyes and purple glasses.
Jeanette was born the middle of the three Chipette triplets in Australia. Luckily, they were taken in the care of by an orphaned human girl named Olivia in an orphanage, until they were kidnapped by Miss Grudge (the runner of the orphanage) and Eva (another orphan). Than the night when Olivia was adopted they all escape to New York where they worked as miserable diner waitresses and lived on the streets until they moved to California and eventually hit the big time.
In Alvin and the Chipmunks: The Squeakquel, not much is known about her early life, before she and her sisters teamed up with Dave and the Chipmunks. It is implied, much like any other chipmunk, they lived in a tree and were in a large population of other chipmunks, implying that there are many more like them.
In Little Alvin and the Mini-Munks, the girls live with Dave along with their counterparts (including Simon), when they first came to Lalu's house Jeanette used Brittany's lipstick without asking and even ate it which leads up to Brittany to tell on her. Then Lalu explains to Jeanette that eating lipstick could be a problem which hints at an early development of the clumsy characteristics that are seen in both the CGI and 1980’s versions of Jeanette.
Jeanette is shown as a preschooler. In this movie her eyes are shown as brown. Her glasses are also purple instead of pink. In this movie, she steals Brittany's makeup and eats it on accident.
Jeanette is an orphan adopted by Ian Hawke and is Simon's love interest. She is a member of the group, The Chipettes, and seems to excel at singing the alto parts. Most of the time, she is shown to have a very timid personality. She is presented to be the most mature and intelligent of their group, though Eleanor is more likely to voice her opinion. However, unlike Alvin to Simon, she and Brittany seem to get along very well. Unlike Eleanor or Brittany, Jeanette has trouble at being an outspoken person and will more often than not choose to keep her thoughts to herself and show obvious fear at simple tasks that may require danger (even if it is just jumping through a mail slot). While the latter is not as big of an issue in the cartoon series as it is in the live action films her shyness is obviously present in both. For example, while Simon and Jeanette are enjoying a blossoming relationship due to their shared interests they both show incredible uneasiness if the subject is brought up. Another trait Jeanette is shown to be struggling with is her timid attitude. Due to this she is shown as being unable to stand up to Ian. She sometimes has shown evidence to be insecure.
Jeanette is not seen to be at all clumsy in this film as she is in the original series. She easily keeps up with her sisters as they perform multiple songs on the ship. Once on the island, Jeanette spends quite a bit of time with Simone. When they dance, she is very steady and doesn't once stumble or fall down. Their time together is quite possibly a date, though it's questionable with who. We see that she is very happy with Simone. Jeanette is pretty open and much more comfortable around him while she is shyer around Simon. After Zoe captures her and they escape to the raft, she is very forgiving of Zoe's actions.
Jeanette isn't brave enough to stand up to Brittany. Brittany pushes Jeanette around a lot and takes advantage of her kindness, but deep down they love each other very much and are very loyal to each other. Brittany gets very defensive of Jeanette when someone else is mean to her, in most situations. Even when Brittany is mean to Jeanette, she is extremely loyal despite her behaving awful towards her, saying "You're my sister, Brittany."
Eleanor always stands up to Brittany when she tries to push Jeanette around, and always defends her when anyone says something negative. For example, refusing to help Brittany join a group that called Jeanette a 'nerd'.
Jeanette and Simon have a very strong relationship. During the series it is a relationship that can be described as best friends who have secret crushes on one another. Simon is always looking out for Jeanette, and he always catches her when she falls (literally!) and stands up for her. Simon seems very protective of Jeanette, and the two of them spend a lot of time together. In Big Dreams, they are shown as married in the future.