Bart is the first of three kids to Homer and Marge, he is the older brother to both Lisa and Maggie. Bart was concieved before Homer and Marge were married at a miniature golf course. Homer and Marge later married after discovering that she was pregnant with their first child, making Bart born in wedlock. Homer cites him as a close call in that regard. Bart's first word came when he saw his parents having sex in their bedroom (possibily concieving Lisa)

At a young age, Bart was an active child, often causing mischief for his parents and often refering to his father by his first name despite Homer wanting to be called "Daddy." Bart has shown that he is capable to achieve great potential if he would concentrate and focus. When he was ten minutes old, he was able to set Homer's tie on fire with his lighter. And when he starts to take Focosyn, he begins to concentrate better but he starts to go mentally insane and destroys a satellite with a tank which he was correct in shooting down.

Bart regularly fights with his sister, Lisa, often because she is smarter than him and he is jealous of her grades. Though the two fight often, they do care about each other, and Bart will come to Lisa's aid should she need his help. Bart recognises Lisa's smarts and often enlists her aid to help solve mysteries regarding Sideshow Bob or reuinte Krusty with his father. In 8F15 - Separate Vocations when Lisa stole all of the Teacher's Editions in the school, Bart took the rap for it and served Lisa's detention for her because he doesnt want her to ruin her life.

Bart is well known for his pranks, and considers himself to be the best prankster of the school. (Though in reality, he's second only to Andy Hamilton.) Bart used to be bullied quite a lot. Typically by Nelson Muntz, but the two later became friends. Bart has a best friend in Milhouse Van Houten, who is often portrayed as Bart's sidekick and often a victim of Bart's pranks.

Bart likes to thoughly enjoy his youth and makes the most of the time he has as a kid. Other than pranking he likes to play video games and watch Itchy and Scratchy. Bart worships Krusty the Clown, and bases his life on Krusty's teachings, because of this, Bart will do anything to help Krusty. Bart also enjoys reading Radioactive Man comics.

Bart has many rivals and enemies, the most notable is Sideshow Bob who is always trying to kill him. Bart is always able to outsmart Sideshow Bob and have him sent back to prison. Bart usually takes Sideshow Bob on with his sister Lisa, but on occation Bart has had to go solo because Lisa either didnt believe him or she was captured along with the rest of the family minus Bart such as in 9F22 - Cape Feare.

Bart has had many girlfriends over the course of the series. Including Jessica Lovejoy, Greta Wolfcastle and Laura Powers, most of the girlfriends he had typically like him because he puts on a new persona, and is not actually himself. The only time he was himself was with Greta, but she dumped him after he lied to her to see Principal Skinner do some lame stand up comedy, she later rebounded to Milhouse, and both boys fight for her. She later dumps both.