Donnie Darko - Ending Explained

The twist is that the entire movie (after the engine crash) takes place in a doom-laden Tangent Universe. Donnie didn't just dodge death; he caused a glitch. Frank (the rabbit) is actually the ghost of the boy Donnie shoots in the future of this timeline. Frank travels back to guide Donnie. In the climax, Gretchen is run over and killed by the real human Frank. Distraught, Donnie realizes he must use his telekinetic powers to rip a wormhole in the sky and send the jet engine back in time to the moment the universes split. He chooses to stay in his bed in the Primary Universe, allowing the engine to crush him. This resets the timeline: Gretchen lives (and doesn't know him), Frank lives, but Donnie dies. The final montage shows the other characters waking up with a vague, haunting memory of the alternate reality, often crying or looking relieved.

The Tangent Universe (Canonical): The Director's Cut confirms that the jet engine crash created an unstable parallel dimension. Donnie is the superhero chosen to guide the engine back to the main timeline to stop the universe from collapsing.

The Schizophrenia Theory: Many viewers interpret the film as a tragedy about a boy succumbing to paranoid schizophrenia. In this reading, Frank is a hallucination, the "time travel" is a delusion of grandeur, and the ending is a suicide caused by his mental break. The film supports this with Dr. Thurman's diagnosis and Donnie's medication.

The Dying Dream: A less popular theory suggests the entire movie takes place in the split second before the engine kills Donnie—a "life flashing before your eyes" fantasy where he imagines a life where he saved the world.