As is often the case, his isn't exactly a name well known in our popular genre circles, but he certainly dipped his toes in here worthy of the mention. One of his earliest guest roles was aboard an episode of TV's Man From Atlantis in 1977; the popular Patrick Duffy program was a short-lived staple while it ran on the Boob Tube. Then, in 1978, Hall made a visit to Terror Out Of The Sky, a telefilm sequel to The Savage Bees. In 1981, there was another telefilm -- This House Possessed -- that saw the man filling out another bit-style part in a Horror property.
1987 came and went, and Hall was cast with a good part in the TV adaptation of The Spirit. Unless I miss my guess, I believe that was originally intended as the pilot film for a TV series; but no series ever materialized. IMDB.com even reports that a write-in campaign had to be staged in order to get the telefilm aired, so I'm guessing it might be all a bit undercooked.
1989 ... well, who you gonna call? Ghostbusters II -- written by Dan Aykroyd and Harold Ramis -- cast the man as New York City's police commissioner (shown above). For what it's worth, the singular voice of authority was exactly the kind of work Hall was best suited for, and I think he returned to it time and time again throughout his over five decades in the business.
Any other genre work?
He enjoyed some screen time aboard M.A.N.T.I.S., Roswell (1994), 3rd Rock From The Sun, Millennium, The Truman Show (1998), Lost Souls (2000), Night Visions, The Amityville Horror (2005), and the short-lived Second Chance.
Prayers are extended to the family and friends of Philip Baker Hall.