He has been married to actress Jean Smart since 1987. They met while working on the set of Designing Women (he played J.D. Shackelford, the boyfriend of her Annie Potts' character, Mary Jo Shively). They have a son, Connor Douglas (born 1989) and a daughter, Bonnie Kathleen (adopted as a baby from China in May 2009). Gilliland played Captain Stan Cotter on 24 while his wife Smart later played First Lady Martha Logan on the same series.
He appeared onscreen in the 1970s. Notable appearances include Thirtysomething, Party of Five, Little Women, and a recurring role on Designing Women (where he met his wife Jean Smart, who starred as Charlene in that series). The couple has one son, Connor. Richard recently played Ellis Kapp on The Unit and Captain Stan Cotter on 24 while his wife Jean Smart played the First Lady Martha Logan in season 5. (He was in episode 2:00am to 3:00am). Gilliland is best friends with actor Joe Mantegna. He was also known for playing Mary Ellen's love interest "Jonesy" in The Waltons and Jeffrey Spidell in Matlock.