(from IMDB.com)

Josh Hartnett …. Dwight McCarthy
Marley Shelton …. Mary
Jaime King …. Goldie/Wendy
rest of cast listed alphabetically
Jessica Alba …. Nancy
Maria Bello …. ???
Kate Bosworth …. Gail
Jason Douglas …. Hitman
Carla Gugino …. Lucille
Brittany Murphy …. Shellie
Mickey Rourke …. Marv
Nick Stahl …. Junior/Yellow Bastard
Makenzie Vega …. Young Nancy
Bruce Willis …. John Hartigan
Katherine Willis …. Nurse Ella Quent, R.N.
Elijah Wood …. Kevin