Keith David
— Narrator (voice)
Kevin Conway
— Mark Twain (voice)
Blythe Danner
— Olivia "Livy" Langdon Clemens (voice)
Philip Bosco
— (voice)
Tim Clark
— (voice)
Carolyn McCormick
— (voice)
Amy Madigan
— (voice)
Cynthia Nixon
— (voice)
John Boyer
— Self (uncredited)
Jocelyn Chadwick
— Self (uncredited)
Shelly Fisher Fishkin
— Self (uncredited)
Dick Gregory
— Self (uncredited)
Hal Holbrook
— Self (uncredited)
Arthur Miller
— Self (uncredited)
Chuck Jones
— Self (uncredited)
Ron Powers
— Self (uncredited)
Laura Skandera-Trombley
— Self (uncredited)
William Styron
— Self (uncredited)