As of this writing, actor Vaughn Armstrong still holds the record for the most number of characters throughout "Star Trek." Jeffrey Combs technically might have Armstrong beat, but that's only if you count multiple identical clones as separate roles. 

Of the main cast, however, Brent Spiner currently holds the record for playing the greatest number of characters. Apart from his central role as the android Data on "Star Trek: The Next Generation," Spiner also played his own evil twin brother, Lore, a Data prototype named B-4 (in "Star Trek: Nemesis"), and the androids' creator Dr. Noonien Soong. On "Star Trek: Enterprise," he played Dr. Arik Soong, an ancestor of Noonien, who was a villain keen on eugenics. In "Star Trek: Picard," he played an even more distant ancestor Dr. Adam Soong, who lived in the year 2024. In both the first and third seasons of "Picard," he also played Dr. Altan Soong,...