Brittany Tenelli is one of Cindy's best friends and Nick's girlfriend. She is often seen singing and dancing with Cindy and Libby as a third member of their circle of friends and hanging out with them in many episodes, but usually appears as a supporting character. She bribed Libby to be her science partner with a music CD in Raise the Oozy Scab because she doesn't know how to read or write. She is very ditzy, clumsy, sweet, innocent and kind. She is one of the few characters who doesn't antagonize Jimmy in any way and she appears to admire him and his brilliance. This makes her a comic foil to the brainy Cindy and Libby and one of Jimmy's few fans. She is very happy-go-lucky, and with her head in the clouds, often confused in a situation. 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.
Brittany is around the same height as Cindy and Libby. She has blue eyes and blonde hair which she has put up in two long pigtail braids. She wears red-pink eye shadow, a white and pink crop top, a pink short-sleeve jacket and pink sneakers. In the movie, she wears bracelets on both of her arms.
- "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
- Being a blonde girl named Brittany who likes to dance, sing and wear navel bearing outfits, her entire character may be a nod to Britney Spears.
- She is illiterate, as we see in Raise the Oozy Scab.
- Aside from being one of Cindy and Libby's best friends, she seems to be close friends with Amber as well.
- Her Planet Sheen counterpart is Princess Oom.
- She has a loud and high-pitched laugh that most of the characters find annoying.
- In the movie, she is seen speaking to an old woman and two adults, presumably her grandmother and her parents.
Main Characters: Jimmy Neutron | Carl Wheezer | Goddard | Sheen Estevez | Cindy Vortex | Libby Folfax | Nick Dean | Goddard | Hugh Neutron | Judy Neutron