Has three sons wife his wife: Jake (b. 1996), Ben (b. 1999), and Sam (b. 2003).

Founder of Band From TV Global Charity Trust. Drummer of Band From TV, comprised of other TV stars including: ABC's Bob Guiney, actor Hugh Laurie, actor James Denton, and actress Bonnie Sommerville.

Created and ran a successful frozen yogurt delivery service.

He has known J.J. Abrams since they were in kindergarten. Greg has gotten parts in almost every project J.J. works on.

Auditioned for the role of Fred Flintstone in The Flintstones in Viva Rock Vegas (2000).

Was originally set play Detective Wallace MacTee in Hero Wanted (2008) alongside Ray Liotta and Cuba Gooding Jr. but was forced to drop out at the last minute due to scheduling conflicts with his role on _Heroes (2006/II)_.

He is the Chair of the National Walk for Epilepsy "2008".

Brother of Brad Grunberg.

Acted in several high-profile television commercials early on in his career, including one that was so memorable it landed him on "The Tonight Show."

One of his children has Epilepsy.