(written from a Production point of view)
Keith Taylor played an Only boy in the Star Trek: The Original Series episode "Miri". He had previously played the recurring role on Harry on the hit television sitcom Leave It to Beaver, a series that also featured Majel Barrett.
Besides Star Trek, Taylor also made appearances on My Three Sons, My Favorite Martian (starring Ray Walston), Lost in Space (with Bill Mumy), Land of the Giants (in an episode with Elizabeth Rogers), and Maude (with Adrienne Barbeau), among other TV programs. He also appeared as a messenger in a 1974 TV version of William Shakespeare's Antony and Cleopatra, co-starring Patrick Stewart and W. Morgan Sheppard, and was seen in such films as Follow Me, Boys! (1966, with John Larroquette), The Perils of Pauline (1967, with Hamilton Camp and Paul Winfield), and The Young Runaways (1968, with Lance LeGault).