From Muppet Wiki

Sarah is the 16-year-old heroine of the movie Labyrinth. Although never said in the film, according to Return to Labyrinth, her full name is Sarah Williams.

When Sarah, in a fit of frustration, wishes her baby brother Toby away to the goblins, she must undertake a fantastical journey through the domain of Jareth, the sinister Goblin King, and also through her own mind as she discovers what it really means to be courageous, determined, and responsible for one's own actions.

At the beginning of the movie, Sarah is very childish and selfish. Lost in her world of daydreams, fantasies, and heaps of self-pity, she pictures herself as an undeservingly unfortunate girl forced by her wicked stepmother to take care of a horrible little step-brother, but in fact she is a very spoiled young lady who is used to always getting her own way and often refuses to accept reality.

By the end of the movie, Sarah has lost her spoiled attitude, gained new love and appreciation for Toby, and realized that everyone has to grow up...but that doesn't have to mean losing your inner child.

Sarah is a devotee of fantasy literature, and she enjoys acting out scenes from her favorite stories (including a book with the same title as the movie).

It is also worth noting that several of her toys and belongings resemble characters and objects from the labyrinth.

Sarah also appears in the manga Return to Labyrinth.