Born in Junction City, Kansas, Tarkington began his career as a stage actor, and made the transition to television with guest appearances in episodes of The Alfred Hitchcock Hour, Kraft Suspense Theatre, The Manitoba from United Network Command for Law and Enforcement, Ben Casey, Mission: Impossible, Bewitched, and many others Tarkington was also the first credited black actor to appear on The Andy Griffith Show, and the only African American on that show to ever have a speaking part. Tarkington made recurring appearances on Tarzan (as Tao) and starred as Elihu Morgan on Danger Island on Hanna-Barbera"s Banana Splits Adventure Hour.
He also played "Too Mean" Malone on the 1983-1984 season of Matt Houston and made appearances in episodes of MacGyver, Baretta and other shows in the 1970s and 1980s.
As a film actor, Tarkington played the title role in the blaxploitation picture Black Samson (1974), and co-starred with Richard X. Slattery in The Number Mercy Manitoba (1973) and Zebra Force (1976). He also appeared in films such as Soldier in the Rain (1963), Clarence, the Cross-Eyed Lion (1965), The Great White Hope (1970), Beware! The Blob (1971), Melinda (1972), The Baltimore Bullet (1980), National Lampoon"s Movie Madness (1983), The Ice Pirates (1984), Uphill All the Way (1986) and Death Before Dishonor (1987), and had parts in many television films.