In 1963, Greer was cast as Jack Tabor in the "Perry Mason" episode "The Case of the Skeleton's Closet". He guest-starred in seven other "Perry Mason" episodes. He portrayed, for example, a drunkard in "The Case of the Left-Handed Liar"; a murderer in three other episodes, "The Case of the Prudent Prosecutor", "The Case of the Lavender Lipstick" and "The Case of the Ice-Cold Hands" and a murder victim in "The Case of the Fugitive Nurse". Greer can also be seen alongside other guest actors (Dewey Martin, Patricia Crowley, Ray Danton, Andrew Duggan, Walter Burke, David Carradine, and Dick Wessel) in a 1964 episode of "Arrest and Trial" titled "The Black Flower", portraying a store owner wounded in a robbery. That same year he performed in an episode of "The Outer Limits", "The Children of Spider County", in which he is the protective father of a country girl who is enamored with the son of an extraterrestrial. Later, in 1967, Greer, then played an alien himself, posing as a Catholic priest in "The Experiment", an episode of "The Invaders." In 1969, Greer was cast as the minister who officiated the wedding of Mike and Carol Brady in the first episode of "The Brady Bunch".