(written from a Production point of view)
Dennis Christopher (born 2 December 1955; age 62) played a Vorta, Borath, in the Star Trek: Deep Space Nine episode "The Search, Part II". He later played Danik, a Suliban, in the Star Trek: Enterprise episode "Detained".
He's also appeared as Paul Dooley's son in both the film Breaking Away and an episode of Law & Order: Criminal Intent, as well as on recurring roles on Angel (as the evil wizard Cyvus Vail) and Profiler (as the "Jack of All Trades"), and guest appearances on NYPD Blue, Six Feet Under, and Roswell.
In the Profiler series, his character's mother, Miriam Newquay, was played by Louise Fletcher. Furthermore, Dennis Christopher played Dr. Martin Ruper in the Sci-Fi channel's The Lost Room in 2006.
In the 1980s, he guest-starred on The Equalizer as Father Nicholas Kostmayer, a Catholic priest and younger brother of series recurring character Mickey Kostmayer, played by Keith Szarabajka, who later played Teero Anaydis on Star Trek: Voyager. It was during December of 2012, Dennis could be seen in the Quentin Tarantino motion picture Django Unchained as Leonide Moguy.