Will Arnett Reveals Which Celebrity Neighbor He and Bradley Cooper Used to Fan Over as Young Actors Living in L.A. (Exclusive)

Will Arnett and Bradley Cooper go way back. 

At the world premiere of Is This Thing On? at the New York Film Festival, Arnett, 55, reminisced about when he and Cooper, 50, lived in the same building at the start of their careers.

“I first met him at a bar here in New York with friends, and we instantly hit it off and became pals,” Arnett tells PEOPLE. “Then we were living in California, and I was looking for a place to stay, and he said, ‘Oh, my neighbor’s moving out of this back building that we shared.’ ”

Of course, without second thought, the Arrested Development actor moved into the same building as Cooper. In fact, he moved into the unit “next door” to the Hangover star.

However, they weren’t the only two actors in the area. The duo also got a look into the life of another film star: Dennis Hopper. 

“We lived in this building, and our doors opened onto this stairwell, and we looked across at Dennis Hopper’s place. And we used to always see Dennis Hopper in his backyard or leaving the back alley in Venice,” Arnett recalls, noting that he and Cooper used to fan out over the Easy Rider actor.

“As young actors, we were like, ‘Oh my god, Dennis Hopper!’ or ‘I saw Dennis Hopper today!’ For us, it was such a thrill.”

Hopper, a two-time Academy Award nominee, died at the age of 74 in 2010.

After decades of friendship, Cooper and Arnett finally joined forces professionally for Is This Thing On?, which follows a couple, played by Arnett and Laura Dern, on the verge of divorce as he gives stand-up comedy a try.

Cooper directs and stars in the film alongside Andra Day, Christine Ebersole, Ciarán Hinds, Sean Hayes and his husband Scott Icenogle, Peyton Manning and Amy Sedaris. 

“It’s very surreal,” Arnett says of working with Cooper for the first time. “The thrill of it and the novelty has not worn off.”

The movie is Cooper’s third as a writer and director, following 2018’s A Star Is Born and 2023’s Maestro.

Searchlight Pictures unveiled the first trailer for Is This Thing On?  back in August. “As their marriage quietly unravels, Alex (Arnett) faces middle age and an impending divorce, seeking new purpose in the New York comedy scene, while Tess (Dern) confronts the sacrifices she made for their family — forcing them to navigate co-parenting, identity and whether love can take a new form,” reads a synopsis for the movie.

The film premiered at the New York Film Festival on Oct. 10 and opens in select theaters on Dec. 19.