Brittany Shapiro Tenelli is a major character in the franchise.
Brittany is a very pretty girl with grayish-blue eyes with red-pink eyeshadow and blonde hair that is worn in two long pigtail braids held together by four pink holders on both sides. She wears a midriff-baring white and pink shirt, exposing her belly and belly button, a pink short-sleeve jacket, pink pants with white and pink waistbands and pink Mary Jane shoes with white socks. In Jimmy Neutron: Boy Genius, she wore gold and white bracelets on both of her arms, one of each color on each arm.
Brittany is a very kind, sweet, ditzy, clumsy, bubbly, bouncy, innocent and perky girl who is one of the few characters that doesn't antagonize Jimmy Neutron in any way and she appears to admire him and his brilliance. This makes her a comic foil to the brainy Cindy Vortex and Libby Folfax and one of Jimmy's very few fans. She is very happy-go-lucky and with her head in the clouds, she's often confused in a situation.
Brittany is also illiterate, meaning she doesn't know how to read or write, so she either has her friends do it for her or pretends that can read. She’s very passionate about the people in her life, and falls to pieces rather easily.
Brittany often has low self confidence and sometimes gets picked on by Cindy and Libby when she tries to get involved with their escapades, but they still love Brittany and the three of them are very close.
- "They're just little puff balls!" - Attack of the Twonkies
- "What'll it be, boys?" - Jimmy Neutron: Boy Genius
- "Uh, I didn't do it!" - See Jimmy Run
- "Oh, my God! Those gems are so gorgeous!" - A Beautiful Mine
- "Excellent choice!" - Jimmy Neutron: Boy Genius
- Brittany is often seen singing, dancing and hanging out with Cindy Vortex and Libby Folfax as a third member of their circle of friends in many episodes.
- Brittany is a parody of Britney Spears due to her name, having blonde hair, her liking to dance and sing, speaks with a valley girl accent and wears midriff outfits (particularly in her "Hit Me Baby One More Time" music video).
- It is revealed in Raise the Oozy Scab that Brittany is illiterate (a person who is unable to read or write) and she often has her friends do her schoolwork or read things for her.
- Sometimes though, she pretends that she can read.
- Aside from being one of Cindy and Libby's best friends, Brittany seems to be close friends with Amber as well.
- Brittany is one of the only people Nick Dean shows any form of love and affection to, along with his mother (not that he wants people to know, since it would ruin his macho reputation).
- Brittany's Planet Sheen counterpart is Princess Oom.
- Brittany has a loud and high-pitched laugh that the characters find annoying.
- In the movie when the kids are reunited with their folks, Brittany is seen speaking to an old woman and two adults, most likely her grandmother and her parents.
- In the planned season four, Brittany was going to have more episodes focusing on her.
- Sometimes, it is hinted that Brittany might have a crush on Jimmy Neutron, unbeknownst to Cindy, who does.
- Brittany's appearance looks like Cindy's original design.
- Brittany's pigtails change position depending on her mood.
Villains: King Goobot V | Professor Calamitous | Eustace Strych | Beautiful Gorgeous | Meldar Prime | Evil Jimmy | The Junkman | Zix, Travoltron and Tee | Baby Eddie | Gortox the Irritable | Dr. Sydney Moist