He is the Goblin King, ruling over the creatures that populate the Labyrinth and the Goblin City at its center. Jareth is smitten with Sarah, the film's heroine. He grants her wish to have her infant stepbrother Toby taken away from her, but to her horror he intends to turn the baby into a goblin. Sarah's quest to retrieve the baby from Jareth drives the film's story.
The goblins of the Labyrinth are loyal to Jareth and seem happy to serve him, but other residents of his kingdom, including Hoggle, Ludo, and Sir Didymus, are eager to help Sarah foil his plans for Toby.
Jareth has a few supernatural powers at his disposal, including the ability to alter his form to that of a white owl, the ability to speed up time, and the ability to move the stars or heavens themselves. His powers are frequently aided by crystals. Jareth has a few musical numbers in the film, including "Magic Dance," "As the World Falls Down," and "Within You."
In Other Media
Labyrinth recently saw a resurgence (2005-2006) in merchandise with a release of clothing and various other items from stores like Hot Topic. Most bear Jareth's likeness or a direct quote of his from the movie.