Nick Offerman is a big part of NBC's Thursday night lineup with his role as Ron Swanson on "Parks & Recreation." On "The Tonight Show," he revealed that he was almost a major part of that lineup more than ten years ago. This was back when he was dating Megan Mullally, who is now his wife. He was hanging around the set of her hit show, "Will & Grace," and got an opportunity to try out for a major role.

“They said, okay, we love you for this part. We can’t give it to you yet. We’ll call you tomorrow," Offerman said. "The next day they called and said, Jim Burroughs had called Woody Harrelson on Monday. Woody just called back, he’s gonna take the part. But you woulda got it if he didn’t call back."

Harrelson played Grace's long-term boyfriend, Nathan, in season four. But Offerman still found his way onto the show that season, and he got to make out with his real girlfriend, instead of her co-star Debra Messing. He played a plumber in the Thanksgiving episode where he got kissed and slapped by Karen.

Now it's Mullally who makes guest appeaerances on Offerman's show, "Parks & Recreation," which just got picked up for a sixth season by NBC. In the meantime, Nick Offerman will be appearing in "The Kings of Summer," premiering May 31 in limited release.

Tune in for new episodes of "The Tonight Show with Jay Leno" every weeknight at 11:35 p.m. ET on NBC.

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