Luther McDonald convinced his son that burglarizing houses of their Christmas gifts was a holiday tradition.

He’s definitely not a nice guy.

Gregory Scott Cummins, however, is … in real life.

On the screen? Well, not often.

The former University of Hawaii punter plays McDonald — a meth dealer and prison inmate — on the long-running FX comedy series “It’s Always Sunny In Philadelphia.”

It’s the latest bad-guy role in a 30-year acting career full of them.

His other current role, however, is that of an honest, regular-guy detective on “Bosch,” a series that has just started shooting its fourth season for Amazon.

“This character is probably the easiest one I’ve ever played because it’s probably the closest to the way I am in real life,” Cummins, 61, said of playing Detective Moore, or “Crate” (his partner is nicknamed “Barrel”).

Usually, though, Cummins — with his huge, intimidating eyes that never seem to blink — is cast as a villain.

In dozens of roles since the 1980s he has shared the screen with a long roster of A-List stars, including Sylvester Stallone, Chuck Norris, Jean-Claude Van Damme, Mark Wahlberg, Tupac Shakur, and most recently Danny DeVito.

He’s rarely received anything close to top billing. But if you’ve watched many action movies or TV series over the years, you’ve probably seen him.

“I started out as a leading man (in plays),” said Cummins, who is 6 feet 4. “In the old days leading men were tall. But that changed, and I got moved to being a bad guy because of my height. I grew my hair out long, got a goatee, and I kept getting jobs.

“Even if you wanted to be a sidekick, or another regular, it helped if you weren’t tall.”

In football, the punter is the ultimate character actor; rarely is he the star, even if he is very good at his craft. After his two years at UH, Cummins was second on the program’s all-time punting average list at 40.66 yards per kick (that’s still good for seventh 39 seasons later).

Cummins started college at Cal near his home in Orinda. He transferred to UH after a falling out with the coaching staff, and hearing that the Rainbows’ new coach, Dick Tomey, needed a punter.

After a solid two years on a team where punting was of paramount importance (Tomey built his program around defense, the running game and field position), Cummins performed well in the 1978 Hula Bowl. But his best pro opportunity, with the San Diego Chargers in 1980, was curtailed by a ripped thigh muscle a week before camp.

“I kept trying football until I was 25. Then took a year and a half to figure out what I wanted to do. I had enough credits from UH, didn’t know didn’t have to apply for the degree,” Cummins said.

So he finished up at Cal, and in 1985 got a master’s in fine arts in acting from UCLA. Cummins credits the versatility that allows him to keep getting parts 30 years later to a strong base in acting fundamentals.

“There’s two things: changing the way you look, and changing the way you feel. You can look at different pictures of me and swear it’s not the same person,” he said. “It comes from not just looking different, but having a different thought in your head. I have about eight or nine different looks. I play the Colombian bad guy in a film, a Russian bad guy in another film, a Nazi redneck in another.”

So now he’s a drug dealer and convict in one show, and a relatively clean-cut veteran detective in another.

He stays in touch with Tomey and his UH teammates. Cummins, Jeff Duva and David Toloumu are leading planning for a big reunion for all of the players during Tomey’s 10 years at Manoa. It will be in Las Vegas the week of the Rainbow Warriors game at UNLV on Nov. 4.

Cummins made a guest appearance in the TV series “Raven” here in 1993.

“My secret little dream was always to get a series in Hawaii, a regular role. I’d never come back and would just live in Hawaii and fly to L.A. when I had to.”

Cummins gets rave reviews from Tomey.

“He contributed a lot to our team when we were just in the beginning for me,” Tomey said. “Greg’s in a tough business and he’s hung in there and he’s done what very few can do.”

Young UH football fans who watch “It’s Always Sunny In Philadelphia” probably had no idea the guy who plays Mac’s dad used to punt for the Rainbows. But Luther has become a cult figure, especially among the under-30 demographic.

“Usually it’s only the college kids or recent college kids who recognize me right off the bat. They have watched those shows so many times, they just start quoting some of my funniest lines,” Cummins said.