July 19 (UPI) -- Marc Maron said he felt the need to leave Joaquin Phoenix alone on the set of Joker while appearing on Watch What Happens Live.
"I met Robert De Niro and he was very nice, kind of shy, you know, not a big talker and Joaquin was pacing," Maron said.
"It was made clear to me that you just sort of leave him over there," he continued. "He was deep in."
Joker is set to arrive in theaters on Oct. 4.
Cohen asked Maron who was the all-time worst guest on his podcast, WTF, and Maron said there have only been difficult guests on the show.
"I get very diplomatic about this because, oddly, even the ones that I'm uncomfortable with, I find interesting," he said before mentioning his infamous interview with comedian Gallagher.
The interview ended early after Gallagher stormed off due to Maron asking him about homophobic jokes that he made in the past.
"I was really not, you know, indicting him," Maron said.
"When he's just alone, one-on-one, he's very shy, very thoughtful, you know seemingly somewhat sad," Maron said about interviewing the late Williams. "He didn't entertain at all, so it was just really what a sweet guy he was."
"It was a misunderstanding. He thought I was being an [expletive]," Maron said. "I think he was being the [expletive]."