Limitless is a 2011 American science-fiction thriller film directed by Neil Burger and written by Leslie Dixon. Loosely based on the 2001 novel The Dark Fields by Alan Glynn, the film stars Bradley Cooper, Abbie Cornish, Robert De Niro, Andrew Howard, and Anna Friel. The film follows Edward Morra, a struggling writer who is introduced to a nootropic drug called NZT-48, which gives him the ability to use his brain fully which helps him vastly improve his lifestyle.

The Dark Fields is a 2001 techno-thriller novel by Irish writer Alan Glynn. It was re-released in March 2011 under the title Limitless, in order to coincide with its 2011 film adaptation.