Originally, it was his half-brother David Carradine who pursued a role in the Broadway musical "Hair" in 1969. At his audition he brought Keith along to play the piano. Keith ended up winning the part and stayed with the show for six months.
Daughter Martha Plimpton was conceived while Keith and actress Shelley Plimpton were appearing in the rock musical "Hair" on Broadway in 1969. Born in 1970, the relationship was over by the time Martha was born and Keith did not meet her until she was four years old.
His recording of "I'm Easy" reached #17 on the US charts in August, 1976.
Father, with Sandra Will, of a boy named Cade Carradine (b. July 19th 1982) and a girl named Sorel Carradine (b. June 18th 1985).
Outer Critic Circles Award winner in 1982 for Broadway debut for "Fox Fire".
Was nominated for Broadway's 1991 Tony Award as Best Actor (Musical) for playing the title character Will Rogers in "The Will Rogers Follies."
Tony Award nominee in 1991 for Best Actor in a Musical for "Will Rogers Follies".
Drama Desk Award nominee in 1991 for Best Actor in a Musical for "Will Rogers Follies".
Longtime girlfriend is Hayley DuMond. Met while filming Hunter's Moon (1995) with Burt Reynolds. 
Plays "Wild Bill Hickock" in "Deadwood" (2004) and played "Buffalo Bill Cody" in Wild Bill (1995).
For his role on "Deadwood" (2004), he was trained by renowned Hollywood Gun Coach Thell Reed, who has also trained such actors as: Val Kilmer, Kurt Russell, Sam Elliot, Girard Swan, Russell Crowe, Brad Pitt, and Leonardo DiCaprio.
On "Criminal Minds" (2005) he played Frank Breitkopf, a serial killer that had been killing for 30 years. On "Dexter" (2006), he played Frank Lundy, who hunted a serial killer that had been killing for 30 years.
Lucille Lortel Award nominee 2010 for Outstanding Featured Actor for "A Lie of the Mind".
He was awarded a Star on the Hollywood Walk of Fame for Live Performance at 6233 Hollywood Boulevard in Hollywood, California.