So when the news broke of Shandling's death last week, at age 66 from a heart attack, it was deeply shocking to not only the entertainment community as a whole but Favreau personally.
The pair worked together several times throughout their careers, most notably in the Iron Man series of films Favreau was at the helm of.
Most recently, he starred as the voice of Ikki in the 49-year-old filmmaker's blockbuster live action take on Disney classic The Jungle Book.
Out in Australia to promote the film, it was a tough subject for Favreau.
"It's still kinda, you know, not that long ago. It feels a little odd... to be thinking about it in those terms," he said.
"Everyone knew what he did in front of the camera, that's no secret: how he changed television with The Larry Sanders Show.
Source: Marvel
"But he was such a vital force behind-the-scenes.
"He'd be the first guy you showed your movie (to) when it was done, not just me but alotta people they'd show their work to.
"He was always encouraging and critical in the most helpful way."
A comedic powerhouse, Shandling had a career that spanned over 40-years in Hollywood as not only a stand-up comic and writer, but actor, producer and director.
Best known for the breakout satirical take on the late night talk show - The Larry Sanders Show - his work on the series went on to influence everything from 30 Rock to Curb You Enthusiasm and launched the careers of stars like Sarah Silverman, Janeane Garofalo and Jeremy Piven.
" ... he was such a vital force behind-the-scenes."
Favreau said one of Shandling's biggest gifts was what he did off camera: bringing people together.
"He really was such a binding force that connected so many people from different aspects of show business that all overlapped and that would go to his house to play basketball or an event or a family function.
"He was quite an athlete and boxing too. See, these are the things you don't know about the guy.
"He was in great shape too, he took very good care of himself so that's why it's so shocking that we lose him so early because he felt so alive and so vital.
"It's very sad and sobering."
The Jungle Book releases in cinemas Thursday, April 7.
Source: AAP
