Lillard grew up in Tustin, California. After high school, he was hired as an extra for Ghoulies 3: Ghoulies Go to College (1991). He attended the American Academy of Dramatic Arts in Pasadena, California and later, the theatre school Circle in the Square in New York City.

In the 1990s, Lillard dated actress Christine Taylor, prior to her marriage to actor Ben Stiller.

Lillard married Heather Helm in 2000, and they have two