Actor Mike Connors, right, with Dick Van Dyke, filming an episode of "Diagnosis Murder" in 1997. (Chris Pizzello/Associated Press)

Mike Connors, a rugged actor who starred as the hard-nosed Joe Mannix in a popular TV detective series of the 1960s and 1970s that broke racial barriers in casting, died Jan. 26 in Tarzana, Calif. He was 91.

He was recently diagnosed with leukemia, his son-in-law, Mike Condon, told news outlets.

Mr. Connors, a onetime college basketball player, was a journeyman actor before being cast in 1967 in the title role of “Mannix,” playing a renegade detective for a high-tech detective agency.

The show was nearly canceled after its low-rated debut season but was saved when Lucille Ball, whose Desilu Productions developed “Mannix,” persuaded CBS executives to keep it on the air.

For the second season, the show was retooled, with Mannix setting up a solo practice as a private investigator in Los Angeles. He was helped by his heroically competent secretary, Peggy Fair (played by Gail Fisher), in one of the first substantial dramatic roles for an African American woman on prime-time television.

“Mannix” star Mike Connors in 2007. (Jonathan Alcorn/For The Washington Post)

“Mannix” went on to have an eight-year run, with Mr. Connors playing a private eye who was always in action, always in trouble. He became one of TV’s highest-paid actors of the time, earning a then-astronomical $40,000 per episode.

“Mannix was the last of a certain type of American manhood, circa early ’70s,” Washington Post reporter Neely Tucker wrote in 2007. “He wore a tie and a wistful smile. He did not know doubt but was a friend of irony. . . . He drove too fast, drank too much and smoked like he got paid for it. He slugged people and shot guys and never got pulled in by the cops.”

“Mannix” had stylish opening credits and a driving musical theme by Lalo Schifrin and was also unusually violent for its time. As Mannix, Mr. Connors was constantly crashing through windows, sliding down drainpipes, being chased by helicopters or having his convertible forced off the road.

According to one count, he was shot 17 times and sustained 55 concussions during the series’ 194 episodes. Mr. Connors did many of the stunts himself and sustained a broken wrist and dislocated shoulder while making the show.

Yet he always managed to climb back in his dark green Dodge Dart (or, later a Plymouth Barracuda, then a Dodge Challenger, then a Chevrolet Camaro) and dial up Peggy on his car phone to let her know he was on the way.

Mr. Connors was nominated four times for Emmy awards and won a Golden Globe. In 1970, Fisher became the first black actress to win an Emmy. As Peggy, she portrayed a single mother whose husband, a police officer, had been killed in the line of duty. Working for Mannix, she went undercover, was sometimes captured by kidnappers and invariably had to nurse her injured boss back to health. Their relationship stopped just short of romance.

Mannix never failed to notice a stylish woman, but if there was a case to be solved, he would leave her standing with a casual “No, baby” or “Maybe later.” Then he was off in his convertible, racing to a criminal hideout to rough up a few crooks and hand them over to the police.

Mike Connors in 2007. (Jonathan Alcorn/For The Washington Post)

“We made the character vulnerable. . . . He could be suckered in by a soft story or a pretty face,” Mr. Connors told the Los Angeles Times in 1997. “I think people thought he was a very normal kind of guy doing a job.”

Mannix occasionally spoke Armenian in the show — a nod to Mr. Connors’s heritage. He was born Krekor Ilevado Ohanian in Fresno, Calif., on Aug. 15, 1925. His father was a lawyer.

Known as Jay Ohanian in his youth, Mr. Connors served in the Army Air Forces during World War II, then attended the University of California at Los Angeles on a basketball scholarship and the G.I. Bill. (He played for the Hall of Fame coach John Wooden.)

At a basketball game, the film director William A. Wellman noticed that the 6-foot-1 Mr. Connors (then Ohanian) had an expressive face and voice and suggested he might have a future as an actor. He switched his college studies from pre-law to theater arts and graduated from UCLA in 1951.

Borrowing his basketball nickname, he was known as “Touch Connors” early in his acting career. (The name Connors appears to have been chosen at random.) He had his first film role in 1952, opposite Joan Crawford and Jack Palance in the noirish “Sudden Fear.” He appeared with John Wayne in the 1953 aviation thriller “Island in the Sky.”

In 1956, he played a shepherd in the biblical epic “The Ten Commandments,” then — adopting the name Mike Connors — starred in the short-lived TV detective series “Tightrope” in 1959 and 1960. He also appeared in several films, playing a gentleman gambler in the 1966 remake of “Stagecoach,” with Bing Crosby and Ann-Margret.

After “Mannix,” Mr. Connors starred in another TV crime drama, “Today’s FBI,” but it was canceled in 1982 after one season. He played an Air Force colonel in the 1988-1989 TV miniseries “War and Remembrance” and guest-starred in several other shows, including “Two and a Half Men.”

Survivors include his wife of 67 years, Mary Lou Wells of Encino, Calif.; a daughter, Dana Condon; and a granddaughter. A son, Matthew Gunnar Connors, died in 2007.

In 1997, Mr. Connors reprised his Mannix role on Dick Van Dyke’s medical mystery drama “Diagnosis Murder.” They combined their experience and wiliness to solve a murder that had remained a mystery in a 1973 episode of “Mannix.”

Reruns of “Mannix” occasionally appeared on television but, over the years, fan clubs and websites devoted to the series sprang up, urging that the series be released on DVD. Many classic detective shows, including “Kojak,” “Columbo” and “Magnum P.I.,” were available, but for some reason “Mannix” stayed in the vault.

“We had a better average [rating] than ‘The Rockford Files’ or ‘Hawaii Five-O’ over eight years,” Mr. Connors told The Post in 2007. “And yet it’s like it never occurred, it never existed, it never happened.”

“Mannix” finally began to appear in a digital format in 2008, introducing Mr. Connors to a new generation of viewers.

Even so, “Mannix” was an unforgettable part of 1970s pop culture. In a 1992 episode of “Seinfeld,” George Costanza — the character played by Jason Alexander — suggested that he and Jerry Seinfeld might have to escape a limousine by jumping out while it was moving.

“Who are you,” Seinfeld asked, “Mannix?”