Born in Virginia, Zachary grew up in six different states before settling in Baltimore, MD at the age of 10. His love for acting stems from his family; his father was an accomplished playwright , director, and university professor; his mother is a professional actress and writer. He first performed onstage at the age of four, and throughout his childhood he appeared frequently in plays at his school, at the college where his father taught, and in local community theaters. At age 13, he made his professional debut in Lillian Helman's Watch on the Rhine at Baltimore CenterStage.

Zachary received his BA from Princeton University and was active in theater on campus, performing with several theater groups and going on three national tours with the renowned Princeton Triangle Club. After college, he moved to New York City, where he appeared in various commercials and plays, and made his television debut as a victim on America's Most Wanted. In 1997 he matriculated at the American Conservatory Theater in San Francisco, from which he received a Masters' Degree in Acting in 2000. After graduating, he returned to New York, where he resumed his work in television, film, Off-Broadway, and at various regional theaters.

In 2008, Zachary's career took him to Los Angeles, where he currently resides with his wife, Jody, and their two cats.