Character actor Barry Jenner, best known for his pivotal role as Admiral William Ross on Star Trek: Deep Space Nine and with credits including recurring roles on Dallas, Knott’s Landing, Family Matters and many others, died on August 9, his family has announced. He was 75.

As news of his passing spread, Jenner’s Deep Space Nine colleague Armin Shimerman, who played the Ferengi bar owner Quark for the show’s entire run, expressed his shock and sadness on Twitter.

My heart is broken.My thoughts are in grief&incomprehension.My good friend Barry Jenner has passed.Condolences to Suzanne&all who loved him. — Armin Shimerman (@ShimermanArmin) August 9, 2016

Hailing from Philadelphia, Jenner’s career kicked off in the 1970s with roles on the soap operas Somerset (from 1974–76) and Another World (from 1976–77), on which he was crucial to a notorious storyline plot to kill long-time character John Randolph. In 1981, he joined Dallas spinoff Knot’s Landing in a recurring role as Jeff Cunningham, ex-husband of Abby Cunningham (Donna Mills). Jenner would later hold a recurring role on Dallas as a different character, Dr. Jerry Kenderson (by this point the two series were unrelated, as the death of Bobby Ewing remained in effect on Knot’s Landing despite the infamous ‘it was all a dream’ reveal on Dallas).

A frequent guest celebrity on 1980s game shows $100,000 Pyramid and Super Password, Jenner continued to work extensively on television into the 1990s. He held a recurring role from 1990-1992 as Lt. Murtaugh, the superior officer to Reginald Vel Johnson’s Carl Winslow on Family Matters, and guested on other series such as Highway to Heaven, Falcon Crest, Hart to Hart, Matlock, V: The Series and Silk Stalkings, and Walker, Texas Ranger.

But it was for his recurring role as Vice Admiral William Ross during the last two seasons of Deep Space Nine that Jenner would be best remembered. A dedicated but morally conflicted senior Starfleet officer during the show’s long “Dominion War” arc, Ross was a means by which the show examined the moral ambiguity lying underneath the high-minded ideals of the United Federation of Planets as it faced defeat and destruction at the hands of a seemingly implacable enemy.

Played by Jenner as a steadfast and determined ally to the show’s main cast, the character was also revealed to be complicit in keeping secret the existence of Section 31, a rogue Starfleet intelligence group whose methods were often as unjustifiable as those of the enemy it was working to defeat. Jenner appeared in 12 episodes total, including the two-part series finale. Remembered as one of the series’ most important supporting actors, he was a popular figure on the convention circuit.

Jenner is survived by his wife, Suzanne Hunt.