Marcus is best known for the role of "Peter Gray", on the long-running CBS drama Judging Amy (1999). Marcus is also an accomplished, professional bass guitarist, playing in several bands in Los Angeles, including the alternative country artist Olivea Watson (2007 Gibson Artist Of The Year). Marcus is also a session musician, and a member of Musician's Local 47. His extensive theater credits include stints on Broadway in Horton Foote's "Young Man From Atlanta", and "Measure For Measure" at Lincoln Center. Off-Broadway, Marcus has appeared in numerous shows at MTC, The Lambs and WPA. Regionally, he has worked at The Guthrie, Seattle Rep., Yale Rep., Long Wharf, over 20 productions at The Williamstown Theater Festival, Hartford Stage, New Jersey Shakespeare Festival, The Goodman, and The Eugene O'Neill Playrights Conference.