Tom Davis, the longtime stand-up comedy partner of Al Franken and a writer who created many of the most memorable sketches on “Saturday Night Live,” including the alien “Coneheads,” which he dreamed up while on LSD, died July 19 at his home in Hudson, N.Y. He was 59.

He had a metastatic tonsil cancer, said his wife, Mimi Raleigh.

Mr. Davis and Franken began writing jokes together as teenagers at the private Blake School in Minneapolis, making mock announcements over the public address system, including a satirical Ku Klux Klan march called “Superpatrioticanticatholicsegregatious.”

They joined “Saturday Night Live” before its debut season in 1975 and shared a single apprentice writer's salary of $350 a week, where they collaborated on sketches culled from politics, pop culture, and the bizarre.

Mr. Davis said he spent a small fortune throughout his lifetime on marijuana, hashish, cocaine, LSD and heroin, and enjoyed the substances with his friends Timothy Leary, John Belushi and Jerry Garcia.

"Saturday Night Live" writer/performers Al Franken, left, and Tom Davis are seen in 1978. (Anonymous/ASSOCIATED PRESS/NBC-TV)

The idea for the “Coneheads” came after a drug-fueled vacation to Easter Island with Dan Aykroyd, where Mr. Davis hallucinated that his own forehead had grown 10 inches.

Mr. Davis created the recurring Steve Martin character “Theodoric of York,” a medieval barber who dispatched sage advice on medicine and the law.

In one skit, Theodoric is called upon to rule judgment against a criminal, John the Tanner, who was accused of adultery.

“You were found guilty of theft and your right arm was cut off,” Theodoric says. “You were found guilty of lying and your tongue was cut out. Now, hmm, adultery.”

One of Mr. Davis’s best-known sketches was the scene in which culinary doyenne Julia Child tries to remain calm after she cuts the “dickens out of my finger.” She bleeds profusely all over her holiday chicken and shrieks, before passing out, “Save the liver! Save the liver!”

In 1990, Franken and Mr. Davis had a falling out and split up. Franken pursued ambitions as a radio pundit and politician — he's now a U.S. senator from Minnesota — while Mr. Davis largely faded into obscurity, recovering from his earlier life as a prolific drug user.

By 2004, Mr. Davis had been reduced to a footnote in comedic history as the answer to a trivia question that stumped record-setting “Jeopardy!” champion Ken Jennings: “He was the comedy partner of Al Franken.”

The pair reconciled by the time Franken became a senator in 2008 and after Mr. Davis had spent three years in a narcotics rehab center.

“If we were Sonny and Cher, he would be Cher,” Mr. Davis once said, noting that he refers to himself as “the guy who held Al Franken back for 20 years.”

Thomas James Davis was born Aug. 13, 1952, in Minneapolis. His father worked for 3M and his mother was the 1950 Queen of the Lakes at the Minneapolis Aquatennial summer festival.

As teenagers, Mr. Davis and Franken performed improvisational comedy at Dudley Riggs’s Brave New Workshop in Minneapolis. In the 1970s, Mr. Davis toured India “as a hippie” while Franken finished college at Harvard. Afterward, they moved to Los Angeles in the early 1970s, doing stand-up as a team.

After playing clubs on the fringes of stardom, the pair hit it big when they were recruited — blindly — by Lorne Michaels in 1975 and became staples of the “Saturday Night Live” writing crew.

The two were largely inseparable and worked in tandem for much of their comedy careers. Franken even named his daughter in his best friend's honor, Thomasin Davis Franken.

Mr. Davis wrote a memoir, in 2009, “Thirty-Nine Years of Short-Term Memory Loss: The Early Days of SNL from Someone Who Was There.” The title, he said, came from the fact that he had spotty memory throughout his life, even before he began using drugs.

Survivors include his wife of 21 years, Mimi Raleigh, of Hudson and Mount Kisco, N.Y., where she owns and operates a veterinary clinic; his mother, Jean Davis, of Minnetonka, Minn.; and a brother.

“On Tuesdays, we'd stay up all night writing,” Mr. Davis once said, “Those were the best and worst times, because it was agonizing. But if you found yourself rolling on the floor laughing at 2 in the morning, that was as much fun as you could have, really, except for getting those huge laughs on-air. . . . And then to be in a restaurant the next day and overhear a conversation at the next table where they are talking about your piece, that's real payoff. That's real fun.”