Forty years after its release, National Lampoon’s “Animal House” is still regarded as one of the best comedies of all time and a quintessential movie for college-bound students. The film, which originated from short stories published in National Lampoon magazine, sits tall at No. 36 on AFI’s Funniest Movies list and has been preserved in the National Film Registry.

However, nobody at the time realized what “Animal House,” which follows a group of rowdy fraternity brothers at the fictional Faber College in 1962, would become.

“[Universal] didn’t really want to make this movie,” Tim Matheson, who played Eric “Otter” Stratton, told Page Six in a recent interview. “Sean Daniel was the young studio exec at the time and he just kept hammering them on this. The studio offered it to, like, five other directors from John Schlesinger to just all the wrong people, and they all turned it down.”

Finally, John Landis signed on to direct the project. Harold Ramis and National Lampoon magazine writers Doug Kenney and Chris Miller originally wrote Matheson’s part for Chevy Chase, while D-Day was written for Dan Aykroyd and Bluto for John Belushi (who would go on to play the part). But Landis wasn’t interested in having an entire cast of “Saturday Night Live” members.

“The studio fought him long and hard on that and he prevailed,” said Matheson, 70. “They had a lunch with Chevy, and Landis kept saying all the wrong things [on purpose]. He said, ‘Oh Chevy, it will be just like ‘SNL.’ You’ll be one of 10 people in the movie and it’s an ensemble. Now, if you do [‘Foul Play’] with Goldie [Hawn], it’s just you and her and it won’t be as fun.’ Chevy walked out of there going, ‘I’m not doing that movie.'”

The hunt for a new Otter began, but the studio also wasn’t interested in having Matheson audition. Matheson said at that point in his career, following a stint on “Bonanza” and “The Quest,” he’d been typecast as a cowboy.

“They just said, ‘No, he’s just not right for this part,'” he said, adding that he was actually first offered the role as Omega president Greg Marmalard. “I just said, ‘No, I’d rather not be in this movie than play that part. I wanna be that other guy. I want to be a Delta.'”

Matheson finally got to audition for Otter in front of Landis alongside actor Peter Riegert, who landed the role of Boon. Landis offered Matheson the role on the spot.

“Animal House” filmed at the University of Oregon in Eugene in the fall of 1977. Matheson, Riegert, Belushi and the other Delta Tau Chi brothers got there a week before production began so they could “bond.” The crew was staying at the Rodeway Inn, where they had their first meet-and-greet dinner.

“We all became Deltas that night,” said Matheson, who remembers meeting Belushi, who died in 1982, for the first time that night. “The thing I remember most about John Belushi was how gracious he was to me … The bond went beyond being just actors and I became a friend to him and he was a great friend to me … He was a great man. He was a wonderful actor.”

Despite the toga parties and incessant drinking in the film, Matheson insists it was all “near beer” and “tea” on set.

“Landis was really strict,” he said. “He told everybody, ‘No drugs! Nobody do anything stupid on this set. We got to work really hard. Do whatever you want to do later, but don’t do it here.’ He was real clear about that and everybody was on their best behavior when we worked.”

However, post-filming and their one day off a week were a different story.

Matheson says Bruce McGill’s (D-Day) room at the motel was “party central.” Kevin Bacon, who played a pledge from the rival Omega frat, told Marc Maron in a 2017 interview, “There was always this amazing f–king party going on that I was never invited to.”

While many of the storylines remain laugh-out-loud to this day, there are some scenes — including Pinto’s questionable night with a young teen and Doug Neidermeyer’s unfortunate fate in Vietnam — that Matheson says probably wouldn’t make the cut in today’s politically correct world.

Talking about the scene at Dexter Lake Club, when the Delta brothers walk into a bar with an all-black clientele, Matheson revealed that the studio was initially concerned about it being racist.

“They showed the movie to Richard Pryor because they wanted to cut [the scene],” Matheson explained. “He looked at the movie and he said, ‘This is great. White people are crazy!’ He loved it. It stayed in because of him.”

“Animal House” was released in July 1978. Little by little, Matheson said, he started realizing just how big the movie was going to be. He said every day something would happen and he would think, “Oh wow, this is cool.”

Matheson recently reunited with Riegert, McGill and other cast members, as well as Landis, in San Francisco to celebrate the film’s anniversary. He is also appearing at the New Jersey Performing Arts Center on Feb. 16 for the movie.

“I must say, I’m a fan of ‘Animal House,’ so it’s nice to remember how really magical it was,” he said. “It really was pretty great.”