- Is the son of Stephen Friedman, who was an executive with Goldman Sachs, an advisor to President George W. Bush and a chairman of the Federal Reserve Bank of New York.
- Was on the wrestling team in high school.
- Wrote a master's thesis on Samuel Beckett.
- Met fellow student D.B. Weiss while attending Trinity College, Dublin. The two became friends and eventually adapted George R. R. Martin's A Song of Ice and Fire series of novels into the TV series Game of Thrones, which debuted on HBO in 2011.
- Worked as a high-school teacher, DJ and club bouncer.
- Wrote a novel as his creative writing thesis in 1999. Titled The 25th Hour, it was published in 2001; he also wrote the screenplay for its 2002 film adaptation.
- Was married in 2006 in New York City at Friends Seminary, a Quaker school his wife, Amanda Peet, attended.