Joe Mannix could take a beating. Over the course of 194 episodes, the hard-boiled investigator suffered countless pistol whippings, conked noggins, gut punches and neck chops. Each time, he shook it off and nabbed the bad guy.

Heck, even the show itself could get knocked down and get back up again. After its first season, in 1967-68, during which Joe Mannix worked for an agency called Intertect, Mannix was suffering low ratings. The show was on the ropes. However, none other than Lucille Ball, who oversaw the series as head of Desilu Productions, believed in Joe Mannix. She adored the character, and saw something of herself in him. Thus, Mannix was given a second chance. Though, the series was heavily retooled. Intertect was scrapped. Joe Mannix suddenly worked alone. The dated 1960s spy-ish elements were stripped away, leaving little more than a rugged PI, a cool car and a hip assistant.

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The adjustments worked. Over the next few seasons, Mannix climbed into the Top 30. Then, in its fifth season, it moved up into the Top 10. Even in its eighth and final season, the series remained a hit, ranking as the No. 20 show on television, pulling in an enviable 21.6 rating.

So, after the eighth season wrapped, in the spring of 1975, Mannix star Mike Connors was optimistic about the future of the CBS series. "I was in New York one week before the new schedule was to be announced, at a CBS party on a Friday night, where they told me not to worry about a thing," Connors recalled in a 2015 interview with Film Talk. "'You’re in; Mannix was picked up.'"

"But the following Wednesday, I got a phone call at about six o’clock in the morning from a writer in New York who said, 'Mike, what have you got to say about Mannix being cancelled?'" Connors continued. "I said, What?! 'Well, they just announced the new schedule and you’re not on it.' I couldn’t believe what I heard."

So what happened? How did a hit show, albeit a veteran one, suddenly get canceled in an about face that even shocked its lead actor? Mannix, believe it or not, was the victim of its own success — and the success of Johnny Carson.

A rival network, ABC, was struggling in late night. NBC had it's juggernaut at 11:30PM, The Tonight Show. CBS, meanwhile, fared well with The CBS Late Movie. ABC, on the other hand, threw everything at the screen to see what would stick in the early 1970s. The Dick Cavett Show was slotted as a headier alternative to Johnny Carson's jovial talk show. After that, the network whipped up ABC's Wide World of Entertainment, a sort of catch-all block that included live rock concerts (In Concert), anthology horror (Thriller), Gerald Rivera, satirical news (Comedy News), mystery movies and cutting-edge British comedy (Monty Python's Flying Circus).

Finally, in 1975, ABC threw its hands in the air and turned to reruns — reruns of action shows. And it even looked to hits from other networks, like NBC's Police Woman and, as you might now suspect, CBS's Mannix. Paramount, which had taken control of Mannix after Desilu, sold previous seasons of Mannix to ABC.

However, CBS was not informed of the deal. Thus, when CBS did hear of Mannix heading to another channel in reruns, the executives soured on the show. The suits figured that reruns on ABC would lessen the appeal of new episodes on CBS. So, the network made the hasty decision to axe the successful action hour. Mannix was canceled.

"Paramount had a dispute with CBS and that’s why we went off the air," Connors himself explained to Film Talk. "… [Mannix] still was a hit show. I was sad, because we had been doing the show for eight years, five days a week, eight months a year and you really become a family. Ninety percent of the crew members that started with the show were still there at the end. I felt very lost when it was over."

In 1997, the character returned to television, in an episode of Diagnosis Murder. "Hard-Boiled Murder" served as a sequel to "Little Girl Lost," a case that had originally aired in 1973. Like we said, you can't keep Joe Mannix down for good. He always gets back up, even if it sometimes takes a couple decades.