Every "Star Trek" episode and film featuring Klingon guest characters.
As the name suggests, the list does not include the appearances of Worf and the half-Klingon B'Elanna Torres, who between them have appeared in all but two episodes of "The Next Generation", 96 episodes of "Deep Space Nine", all but four episodes of "Voyager", eight episodes of "Picard" and the four TNG films.
Even as guest characters, however, Klingons have made more appearances in the franchise than any alien race besides the Vulcans. Of the thirteen films, "The Wrath of Khan", "Star Trek" (2009) and "Beyond" are the only ones in which they do not appear.
Counting Worf and B'Elanna's appearances, they appeared in every "Star Trek" season from 1966 to 2005 with the exception of "Enterprise" Season Three.
The list does not include episodes featuring holographic or illusory Klingons.
