(written from a Production point of view)
Lessing was also seen in three episodes of the Western series The Virginian, including one with Parley Baer and another with John Anderson. Additionally, he appeared in two episodes of I Spy: one with Roy Jenson and Lawrence Montaigne in 1966, and another with Diana Muldaur and Kenneth Tobey.
He and Dick Miller made uncredited appearances in the 1965 film The Girls on the Beach. That same year, Lessing had the romantic lead in the B-horror movie The Beach Girls and the Monster, co-starring Walker Edmiston. Lessing also wrote and performed a song for that film entitled "More Than Wanting You". (Edmiston co-wrote another song for the film.)
Lessing was last seen in a 1971 episode of The F.B.I., in which fellow TOS guest actor Stephen Brooks starred from 1965 to 1967. He is also an accomplished flamenco guitarist and taught guitar at Santa Monica College since the early '70s. He recently retired from his position.