Who lived in the apartment in the building across from Monica's apartment in the American TV series "Friends"?

Ugly Naked Guy (Jon Haugen) is an obese tenant in the apartment in the building across from Monica's apartment—who frequently, perhaps invariably, is naked with the drapes open—so the gang is frequently commenting on his activities—playing cello, wearing "gravity boots", etc. He is first mentioned in the second episode of the series, but only appears twice: first, his belly and an arm are shown in "The One with the Giant Poking Device"—in which he is being poked from across the street by the gang (who think he is dead) with a long device made from chopsticks; second, a rear view of him from head to waist is shown in "The One Where Everybody Finds Out" (his final show)—in which he is moving out of his apartment and Ross tries gets the apartment by ingratiating himself with Ugly Naked Guy by cavorting with him in the nude. (In "The One with the Flashback", it is learned that he used to be "Cute Naked Guy", but then, in 1993, started putting on weight.)

For many years, the identity of the actor that played him in his extremely limited appearances was a mystery. It was speculated that Michael G. Hagerty, the actor who played Mr. Treeger, was Ugly Naked Guy. However, Hagerty denied this theory. On May 31, 2016, an article was published by Todd Van Luling in "The Huffington Post", detailing his search for the identity of Ugly Naked Guy. His article revealed that an actor named Jon Haugen played the role.