The Holographic Doctor questions his own existence in an episode of Voyager that aired on this day in television history.
“Projections” is the 3rd episode of the 2nd season of Star Trek: Voyager. Written by Brannon Braga, the episode aired on September 11th, 1995 on UPN.
In the episode, the Doctor seems to be the only one left onboard after an apparent Kazon attack forced the crew to abandon ship. He eventually finds survivors, but they disappear and encounters and events lead him to believe that he may be a real person and everyone else may be holographic instead!
Dwight Schultz appears as the character Reginald Barclay, a recurring character from Star Trek: The Next Generation. In another connection to that show, the episode was directed by Jonathan Frakes, who played Commander William Riker throughout the series.