Son of noted writer/director/producer Tom Gries and actress Mary Munday. His paternal step-grandfather was jazz musician Muggsy Spanier (who was married to Jon's grandmother, Ruth).
Does not drink milk and eats very little red meat.
In one of his appearances on Seinfeld (1989), he plays a homeless man that refuses to give Kramer's (Michael Richards) Tupperware back. In Napoleon Dynamite (2004), his character is a door-to-door salesman of Tupperware-like products.
On Lost (2004) he played the father of Michael Emerson, who is actually 3 years older than him.
On his definition of success: It's not about the money. It's not about the prestige or being recognized. It's about doing work that you really think has integrity.
On Napoleon Dynamite (2004): The fun of this kind of experience, which I think, unfortunately, a lot of people in the film industry miss, is really the adventure of making a movie that is being nurtured almost like a child and having to go through a channel where there are not millions of hands kind of massaging it to the screen.
(On Get Shorty) I was probably the 250th person they saw for that. They saw Matthew McConaughey, Steve Buscemi, a lot of people. Getting it was kind of an anomaly. It's very difficult being nobody and getting a part in a movie like that. My personal feeling is that what I did in the audition didn't translate on film, and part of that was Barry Sonnenfeld's insecurity. There was so much dialogue, so he thought everything should be sped up. He kept saying, "Make it faster," and I think it lost something. When we had the cast and crew screening, there wasn't a peep from the audience. Barry was sweating profusely. He thought everyone hated it. I walked out of there thinking it was gonna be a big flop. Of course, seeing it now, I think it worked just fine, and we were all being too hard on it.