[3] Ankrum was cast in supporting roles as stalwart authority figures, including scientists, military men (particularly United States Army officers), judges, trail hands, bankers, and even psychiatrists in more than 270 films and television episodes.

Ankrum appeared in such westerns as Ride 'Em Cowboy in 1942, Vera Cruz opposite Gary Cooper and Burt Lancaster, Apache (1954), and Cattle Queen of Montana with Barbara Stanwyck and Ronald Reagan.

In the science fiction genre, he appeared as the rocket project leader in Rocketship X-M (1950); as a Martian leader in Flight to Mars (1951); in Red Planet Mars (1952), playing the United States Secretary of Defense; in the cult classic Invaders From Mars (1953), playing a United States Army colonel; as Army generals in Earth vs. the Flying Saucers (1956) and Beginning of the End (1957); as a psychiatrist in the cult classic Kronos (1957); an Air Force general in The Giant Claw (1957); President Ulysses S. Grant in From the Earth to the Moon (1958); and an archeologist in the independent production Giant from the Unknown (1958).

Ankrum played an embittered rancher named Cash Billings, who allowed hired gunman Burr Fulton ( Rhodes Reason) to take over his spread, but Sugarfoot arrives to bring law and justice to the situation.

The same year, he portrayed a zealot who abused his daughter, played by Sherry Jackson, in the episode "The Naked Gallows" of the western Maverick with Jack Kelly and Mike Connors.

While busy in films and television, Ankrum was still involved in live theatre and continued to direct plays at the Pasadena Playhouse.

[1][8] His final appearance on Perry Mason, in the episode "The Case of the Sleepy Slayer", and his last feature film, Guns of Diablo, in which he was cast as Ray Macklin, were released in 1964 and 1965, respectively, following Ankrum's death.