There is no mystery to John Ritter’s appeal. People just liked him.

That was clear in a lot of conversations Friday after the news came out that Ritter had died Thursday of a torn aorta, six days shy of his 55th birthday.

Yes, he was a good actor, and much admired. He counted among his friends Stan Freberg, the venerable American humorist.

Ritter was also a huge television star, notably as the lecherous Jack Tripper on “Three’s Company,” and won an Emmy for that performance.

Even after that show faded into a short-lived sequel called “Three’s a Crowd,” Ritter kept going in productions of varying success and quality, including the current ABC comedy “8 Simple Rules for Dating My Teenage Daughter.” For younger viewers and their parents, he was the voice of Clifford the Big Red Dog in the PBS series.

He was also part of a show-business dynasty, as the son of singer Tex Ritter and the father of Jason Ritter, a co-star in the upcoming CBS drama “Joan of Arcadia.”

But mostly his success came from that likability. An unlikable Jack Tripper is a creep. And Ritter did not just play likable. He often was, off camera, when he did not have to be — “the nicest person I ever worked with,” one veteran TV publicist said Friday.

“I loved the man,” said Chris Mann, author of “Come and Knock on Our Door,” a history of “Three’s Company.”

Mann recalled putting together a fanzine about the show while in college and sending it to the actors on the show. Only Ritter replied, agreeing to an interview then and, later, a long one for the book.

And overall, the book praised Ritter — because in more than 60 interviews, Mann found that people had almost nothing bad to say about the actor.

While the show took its hits from critics, “in the end … he realized what joy that show brought to people,” Mann said.

It was a joy that did not at first seem likely for Ritter, who told me in 1996 how early in his career he had been pegged as a dramatic actor.

“I started out just doing dramas,” he said. “I played bad guys on ‘Kojak’ and ‘Hawaii Five-O.’ And I was the minister on ‘The Waltons.’ When I got this little part on ‘The Mary Tyler Moore Show,’ I was thrilled to break into comedy.”

He did do dramatic turns from time to time throughout his career. When we talked, he was playing a wife-beating salesman in a TV-movie.

But he knew that it was his personal charm that worked most to his advantage, and he used that to the fullest as a light comedian.

Sometimes he brought comedy to more serious fare, as in a hilarious guest shot on the drama “Breaking News.” He even worked on comedy behind the scenes, as a producer on the Jamie Lee Curtis-Richard Lewis sitcom “Anything But Love.”

But there were obviously times when his life was no laughing matter. A close to 20-year marriage to actress Nancy Morgan ended in divorce. (At the time of his death, he was married to actress Amy Yasbeck.)

“Three’s Company” became legendary for its backstage melodramas as Suzanne Somers tried to declare herself its biggest star, and Ritter dealt poorly with co-star Joyce DeWitt when he left her behind for “Three’s a Crowd.”

Nor could Ritter match the success of “Three’s Company” — still shown in rerun on TV Land — with shows like “Hooperman” and “Hearts Afire.”

Even “8 Simple Rules” was a modest success, ranking 35th in the Nielsens in its first season.

But Ritter kept trying to get people to like him. Sometimes he tried a little too hard, offering up jokes when people wanted something serious. But far more often than not, people did like him. And TV will grieve for his absence.

This story appeared in The Daily Herald on page D2.