Adolf Hitler (20 April 1889–30 April 1945; age 56) made two uncredited appearances as "himself" in two different Star Trek series via archival footage or digitally augmented archival footage.
His first appearance was in the Star Trek second season episode "Patterns of Force", where his doppelganger appeared among a number of Ekosians in newsreel footage. This footage was taken from the 1934 Nazi propaganda film Triumph of the Will.
His second "appearance" was in the Star Trek: Enterprise fourth season episode "Storm Front, Part II", which consisted of digitally altered footage of Hitler in Paris, where the Eiffel Tower was removed and replaced with the Statue of Liberty, making it appear as if he was in New York City. Further footage of Hitler shown in the episode was again taken from Triumph of the Will.
In Gene Roddenberry's original story for the episode "The Savage Curtain", Hitler was among the historical people recreated by the Excalbians to fight as the "evil" team opposing Kirk and the people representing the "good" ideals. (These Are the Voyages: TOS Season Three [page number? • edit])
The Star Trek Encyclopedia, 4th ed., vol. 1, p. 338 misspelled Hitler's first name as "Adolph".