Michael Landon (1936 - 1991) is an actor best remembered for his roles on Little House on the Prairie, Bonanza, and Highway to Heaven.
In 1970, Landon appeared in an insert with Bonanza co-stars Lorne Greene and Dan Blocker on Episode 0131 of Sesame Street, counting to twenty.
They also appeared in Episode 0171, saying the alphabet, and in Episode 0184, subtracting horses.