Born in Inglewood, California, United States, Ellison attended Redondo Union High School, where he starred as a running back and linebacker.

Ellison graduated a semester early from high school and enrolled at USC in the spring of 2005 to pursue a social science economics degree.

During his freshman season he spent most of his time as a back up safety and on special teams, and was selected to The Sporting News Pac-10 All-Freshman first-team.

[5] On May 24, 2010, Ellison was arrested on possession of a controlled substance in Redondo Beach, California after a bottle of unprescribed vicodin pills that he was taking for a recent knee injury was discovered in his car during a routine traffic stop; the charges were later dropped.

[6] On June 14, 2012, Ellison was arrested again, this time for arson after starting an apartment fire in Liberty Lake, Washington which caused an estimated $50,000 worth of damage to the building.

In September 2019, researchers at Boston University posthumously determined that Ellison had Stage II chronic traumatic encephalopathy from studying tissue samples of his brain.