"D.P.O." is the third episode of the third season of television series The X-Files. The episode first aired in the United States on October 6, 1995, on Fox, being written by Howard Gordon and directed by Kim Manners. The episode is a stand-alone episode, like most episodes of The X-Files, and follows the normal Monster-of-the-Week pattern of the show. "D.P.O." earned a Nielsen household rating of 10.9, being watched by 15.57 million people in its initial broadcast, and received positive reviews.

The show centers on FBI special agents Fox Mulder (David Duchovny) and Dana Scully (Gillian Anderson) who work on cases linked to the paranormal, called X-Files. In this episode, Mulder and Scully investigate a series of lightning-related deaths in Oklahoma, which are eventually connected to the only person to have survived a lightning strike, an emotionally charged youth.

The original concept for the episode was a one line concept card stating "Lightning Boy" that had been tacked to a board in series creator Chris Carter's office since the first season. The episode contained several scenes of elaborate lightning effects. Notably, a "lightning machine" used for the sequence where Darin is struck by lightning was created by Special Effects Supervisor David Gauthier and buried under the ground.