Oroku Seifer was a Starfleet officer and joined Trill to the Seifer symbiont in the early 25th century. He commanded the Federation starship USS Phoenix-X until mid-2410, after which he had a short stint as Security chief on Earth Spacedock before finally taking command of the USS Ragnarok. (Star Trek: Phoenix-X, Star Trek Online: Literary Challenge, Earth Spacedock)