Threshold is a science fiction drama television series that ran on CBS from September 16 to November 22, 2005. Produced by Brannon Braga, David S. Goyer and David Heyman, the series focuses on a secret government project investigating the first contact with an extraterrestrial species.

The series was first shown on Friday nights, but was moved to Tuesday in an effort to boost ratings. This plan backfired, with the show registering a sharp drop in its ratings on its first Tuesday night showing on November 22, 2005, and CBS canceled the series on November 23, 2005, leaving four episodes left unaired.

The last four episodes were aired on Sky1, a channel in the United Kingdom owned by Sky, who co-produced the series with CBS. The entire series was released on DVD on August 22, 2006.