Watch Judd Apatow Praise Garry Shandling's Mysterious Genius in HBO Doc

Four-hour 'The Zen Diaries of Garry Shandling' also features guest spots from Jerry Seinfeld, Jay Leno, Conan O’Brien, Jim Carrey, Sarah Silverman

Judd Apataow praises Garry Shandling's mysterious genius in a preview HBO's upcoming documentary about the stand-up comic/TV star.

Judd Apatow talks about his relationship with his comic hero Garry Shandling in the trailer for new HBO documentary The Zen Diaries of Garry Shandling. "In over 25 years, he was the most important mentor that I had," says Apatow. "But in a lot of ways, he was a mystery to me."

The four-hour project chronicles Shandling's career from a rising stand-up comic to a television star on The Larry Sanders Show, using his private journals – kept from age 25 until his death at 66 – as a mirror to view his life.

"Garry was working on a project at one point where he was trying to figure out how to use his journals as a way to talk about his journey in comedy," Apatow told Entertainment Weekly. "In the journals he talks about putting a book out called The Zen Diaries of Garry Shandling. I felt like it was something he wanted to share with people."

The trailer also features guest spots from several comedy giants, including Jim Carrey, Sarah Silverman and Jerry Seinfeld, who tease Shandling's stand-up finesse, career frustrations and late-life move into Buddhism. "He turned to buddhism, but it's not because he's zen," Silverman says. 

"It's because he was in desperate need of being zen." Elsewhere, in an appearance on Seinfeld's web series Comedians in Cars Getting Coffee, he outlines his pure comedic intentions: "Your material is purely a vehicle for you to express your spirit," he says. "It doesn't have any value beyond you expressing yourself in a very soulful, spiritual way. It's why you're on the planet."

Apatow – who wrote for the groundbreaking Larry Sanders Show from 1993 to 1998 – also recruited guest spots from Conan O'Brien, Jay Leno, Jim Carrey and Sacha Baron Cohen, among others. The first installment of the doc premieres Monday, March 26th on HBO, followed by the second half on the 27th.