Sloyan has also appeared in a number of science fiction television series, including Buck Rogers in the 25th Century, in which he portrayed Barnard "Barney" Smith in the episode "The Plot to Kill a City", as well as several roles in the Star Trek franchise. In Star Trek: The Next Generation, he portrayed Alidar Jarok (a defecting Romulan admiral) in "The Defector", and Alexander Rozhenko (Worf's son) as an adult in the Future, in "Firstborn". In Star Trek: Deep Space Nine, he portrayed the Bajoran scientist Mora Pol and Odo's "father" in the episodes "The Begotten" and "The Alternate". The Star Trek: Voyager episode entitled "Jetrel" featured Sloyan as the title character.