Robert L. Hess is an American chess Grandmaster. As of July 2009, his FIDE rating was 2560.

Hess achieved his final norm for the International Master title at the 2007 Cannes Open, and was later awarded the title by FIDE.

Hess achieved his first grandmaster norm at the 2008 Foxwoods Open, held on April 19, 2008 through April 23, 2008 at the Foxwoods Resort in Mashantucket, Connecticut. He scored 7-2, tying for first with grandmasters Alexander Shabalov, Yury Shulman, Julio Becerra, and Alexander Ivanov. Hess won his first two games against masters, then played seven grandmasters, scoring four wins, two draws, and one loss. His performance rating for the tournament was approximately 2770 USCF. Chess journalist Jerry Hanken called Hess's achievement "one of the greatest performances by an American teenager since the heyday of Bobby Fischer!"

In April 2009, he won his third and final grandmaster norm in the Foxwoods Open, soon after winning the SPICE Spring Grandmaster Invitational (where he won his second GM norm) and the K-12 SuperNationals tournaments. In the 2009 US Chess Championship in May 2009, Hess tied for second with Alexander Onischuk, with a score of +5=3-1, losing only to eventual winner Hikaru Nakamura.

Hess is a student at Stuyvesant High School in New York. In the 2007-08 school year, he was a sophomore and the co-captain of the school's junior varsity football team, on which he was a starting linebacker.