Question: What was Richard Dean Anderson famous from before Stargate?

Context paragraphs:
Stargate SG-1 (season 6): Season six of "Stargate SG-1", an American-Canadian television series, began airing on June 7, 2002 on Sci Fi.  The sixth season concluded after 22 episodes on February 19, 2003 on British Sky One, which overtook the Sci-Fi Channel in mid-season.  The series was developed by Brad Wright and Jonathan Glassner.  Season six regular cast members include Richard Dean Anderson, Amanda Tapping, Christopher Judge, Corin Nemec, and Don S. Davis.

Stargate SG-1 (season 8): Season eight of "Stargate SG-1", an American-Canadian military science fiction television series, began airing on July 9, 2004 on the Sci Fi channel.  The eighth season concluded on February 22, 2005, after 20 episodes on British Sky One, which overtook the Sci Fi Channel in mid-season.  This was the first season of the show to have 20 episodes instead of 22, as well as the first to air concurrently with "Stargate SG-1" spinoff series "Stargate Atlantis" (the first season thereof).  The series was originally developed by Brad Wright and Jonathan Glassner, while Brad Wright and Robert C. Cooper served as executive producers.  Season eight regular cast members include Richard Dean Anderson, Amanda Tapping, Christopher Judge, and Michael Shanks.  The eighth season begins with the SG-1 team trying to revive Colonel Jack O'Neill (Richard Dean Anderson) after the events of the seventh season.  At the end of the two-episode season opener, Colonel O'Neill is promoted to General and assumes command of Stargate Command (SGC), while Major Samantha Carter (Amanda Tapping) is promoted to Lieutenant Colonel and assumes command of SG-1.  The season arc centers on the growing threat and seemingly final defeat of the Goa'uld and the Replicators, races who were introduced in the first and third season of the show, respectively.

Doomsday Virus: Pandora's Clock (also known as Doomsday Virus) is a 1996 NBC miniseries based on a novel by John J. Nance about a deadly virus on a Boeing 747-200 from Frankfurt to John F. Kennedy International Airport.  Directed by Eric Laneuville, the film stars Richard Dean Anderson, Stephen Root, Jane Leeves, Robert Loggia and Daphne Zuniga and the script closely follows the book.

Stargate SG-1 (season 2): Season two of "Stargate SG-1", an American-Canadian television series, began airing on June 26, 1998 on Showtime.  The second season concluded after 22 episodes on February 10, 1999 on British Sky One, which overtook Showtime in mid-season.  The series was developed by Brad Wright and Jonathan Glassner, who also served as executive producers.  Season two regular cast members include Richard Dean Anderson, Michael Shanks, Amanda Tapping, Christopher Judge, and Don S. Davis.

Angus MacGyver: Angus MacGyver (known as just MacGyver, or Mac) is a title character and the protagonist in the ABC television series "MacGyver".  He is played by Richard Dean Anderson.  MacGyver works as a problem solver for the fictional "Phoenix Foundation" in Los Angeles.  Educated as a scientist and with a background from a fictional United States government agency, the Department of External Services (DXS), he is a resourceful secret agent able to solve a range of problems.  In addition to his scientific knowledge and inventive use of common items, he always carries a Swiss Army knife and a roll of duct tape.  He prefers non-violent conflict resolution wherever possible and refuses to carry a gun but will sometimes use one (such as the AK47 rifle that he used briefly in the pilot episode).  Lucas Till portrays a younger version of MacGyver in the rebooted 2016 TV series.

List of awards and nominations received by Richard Dean Anderson: List of awards and nominations received by Richard Dean Anderson

Stargate SG-1 (season 7): Season seven of "Stargate SG-1", an American-Canadian television series, began airing on June 13, 2003 on Sci Fi.  The seventh season concluded after 22 episodes on March 9, 2004 on British Sky One, which overtook the Sci-Fi Channel in mid-season.  The series was developed by Brad Wright and Jonathan Glassner.  Season seven regular cast members include Richard Dean Anderson, Amanda Tapping, Christopher Judge, Michael Shanks, and Don S. Davis.

Stargate SG-1 (season 4): Season four of "Stargate SG-1", an American-Canadian television series, began airing on June 30, 2000 on Showtime.  The fourth season concluded after 22 episodes on February 14, 2001 on British Sky One, which overtook Showtime in mid-season.  The series was developed by Brad Wright and Jonathan Glassner.  Season four regular cast members include Richard Dean Anderson, Michael Shanks, Amanda Tapping, Christopher Judge, and Don S. Davis.

Jack O'Neill: Jonathan J. "Jack" O'Neill, Colonel (later promoted), USAF, is a fictional character in military science fiction franchise "Stargate", and primarily one of the main characters of the television series "Stargate SG-1".  He is most known as portrayed by actor Richard Dean Anderson, who played O'Neill in all the "Stargate" media since 1997, when he took over the role from actor Kurt Russell, who portrayed the character in the original "Stargate" film in 1994.  O'Neill and Daniel Jackson are the only two characters to appear in both the original film and all three "Stargate" television series.

Richard Dean Anderson: Richard Dean Anderson (born January 23, 1950) is an American actor and producer.  He began his television career in 1976, playing Dr. Jeff Webber in the American soap-opera series "General Hospital", then rose to prominence as the lead actor in the television series "MacGyver" (1985–1992).  He later appeared in films such as "Through the Eyes of a Killer" (1992), "Pandora's Clock" (1996), and "Firehouse" (1997).

Supporting paragraphs: Stargate SG-1 (season 7) Richard Dean Anderson
Answer: the television series "MacGyver" (1985–1992)