According to Milhouse, Lisa's eyes are gray, but according to Spud Cooder in "Bart Carny", Lisa's eyes are blue. This may indicated Milhouse is color-blind, though could just be an inconsistency.

Although she is always desperate for a boy (saying she will never have love life), she never seems to remember that she has been in a relationship with Colin and several others.

Her romantic relationship with Nelson Muntz has been mentioned or referred to throughout the series, evident in "Lisa's Date with Density", "Love, Springfieldian Style", "Dial "N" for Nerder", "Simpsons Tall Tales", "Sleeping with the Enemy", "Wild Barts Can't Be Broken" and "Elementary School Musical".

In Chief Wiggum's records on the Springfield Mafia, Lisa is listed as a "possible romantic link" to Fat Tony's son Michael, whom she had been friends with in "The Mook, the Chef, the Wife, and Her Homer".

She speaks Italian, due to the help of Milhouse Van Houten.

She has an IQ of 156.

Lisa is a member of MENSA and PETA.

In "To Surveil With Love", she dyed her hair brown to prove that the judges were biased against blondes.

Her email is revealed in "The President Wore Pearls" as

Not many realized that Lisa is still wearing her braces, it couldn't be seen since it was created almost invisible by Calvin Klein.

Early on, before she became a vegetarian, fried shrimp was indicated as her favorite food.

She, along with her her sister Maggie, are obsessed with The Happy Little Elves television show, much to Bart's dismay and disproval. She ususaly responds to his thoughts by saying he's just like Gloomy and Chilly.

Milhouse Van Houten is Lisa's far cousin because Eliza Simpson married with Milford Van Houten.

In Treehouse of Horror XX, it is revealed that her godmother is Helen Lovejoy.

In Holidays of Future Passed, Lisa is shown with three different women, holding their hands. It is heavily implied they are her girlfriends.

In No Loan Again, Naturally , Bart jokes that Lisa is gay. Instead of rebutting that claim, she sarcastically remarks "I'd hate to be gay like my heroes."

Even in episodes after she becomes a vegetarian, there are rare instances where her plate has meat. She does not eat them though.

Lisa is the only Simpson child to appear in every episode.

Her voice actress Yeardley Smith, is one of the only main actors on the show to only voice one character, the other one was Marcia Wallace who voiced Edna Krabappel.

Lisa is right-handed.

She knows how to skateboard.

In Boy Meets Curl, her pearls were revealed to be a gift from Marge when she was first able to read at a twelfth grade level