Stardust (2007)

To win the heart of his beloved (Sienna Miller), a young man named Tristan (Charlie Cox) ventures into the realm of fairies to retrieve a fallen star. What Tristan finds, however, is not a chunk of space rock, but a woman (Claire Danes) named Yvaine. Yvaine is in great danger, for the king's sons need her powers to secure the throne, and an evil witch (Michelle Pfeiffer) wants to use her to achieve eternal youth and beauty.