"Unending" is the season finale of the tenth season and series finale of the science fiction television series Stargate SG-1, and the show's 214th episode overall. Written and directed by Robert C. Cooper, the episode originally premiered in the United Kingdom on Sky One on March 13, 2007, and in the United States on June 22, 2007, on the Sci Fi Channel. The episode attracted approximately 2.2 million viewers on its American broadcast, a ratings success for the Sci Fi Channel.

The episode begins with the mass suicide of the Asgard race, who try to preserve their legacy by giving all of their accumulated knowledge and technology to the SG-1 team and the crew of the Earth ship Odyssey. When the ship is attacked by Ori warships, Lieutenant-Colonel Samantha Carter creates a time dilation field. The field was programmed so while only fractions of a second had passed outside of the field, It takes fifty years inside the field until a defense against the Ori weapons can be found.