Meaning: an officially-recgonised continuaton series utilising either the some or all of the original cast of a series and/or using the same premise and/or set in the same town / country / universe as television series already (or recently) on-air. Spin-offs are usually produced by the same production company / team responsible for the originating series.
- "Stargate Atlantis" is a spin-off of "Stargate SG-1"
- "Star Trek Deep Space Nine" was a spin-off of "Star Trek: The Next Generation"
- "Star Trek Voyager" was a spin-off of "Star Ttek Deep Space Nine"
- "Crusade" was a spin-off of "Babylon 5"