Though she was equally at home in dramas and comedies, screen legend Cloris Leachman will always be remembered for her hilarious portrayal of Phyllis in The Mary Tyler Moore Show followed by her own spinoff. She also played the frighteningly funny Frau Blücher in the classic Mel Brooks film Young Frankestein. A few years before these famous roles, Leachman guest starred on Adam-12 in a part that was about as serious as it gets – a pill-addicted mother who endangers her children.

Beloved by millions as kooky Uncle Fester in The Addams Family, Jackie Coogan wore a mustache and a much more serious demeanor as a football trainer in Adam-12. Coogan’s character was attacked by a burglar raiding the team’s medicine cabinet. Though Coogan plays it straight, it’s impossible not to hear a little bit of Uncle Fester in the way Coogan indignantly rebuts Reed and Malloy’s questioning.

Because Larry Linville’s most famous character, Major Frank Burns in M*A*S*H, took himself so seriously, it’s not hard to imagine the actor in non-comedic roles. But make no mistake, playing the straight man takes the same comedic talent and timing as the one cracking jokes. In Adam-12, Linville plays it straight without any comedic affect as a detective who looks down on beat cops like Reed and Malloy.

Though he was a TV character actor for decades, Art Metrano is perhaps best known for his hilarious role in the second and third Police Academy movies. He played Mauser, a lieutenant and eventually commandant who fell victim to various pranks pulled by the officers he oversaw. In Adam-12, Metrano played a serious role on the other side of the law as a thug in sunglasses who hates cops because an officer shot his brother.

Donna Douglas delighted millions for nine seasons as the sweet and funny Elly May Clampett in The Beverly Hillbillies. Elly had an undeniable southern twang and brought all kinds of furry friends into the Clampett’s mansion. Two years after Hillbillies ended, Douglas appeared in Adam-12 as a woman whose only similarity to Elly May was her large house. Douglas had no hint of an accent and the silliness audiences had been accustomed to was gone as she told Reed and Malloy about a prowler in the neighborhood.