For nearly 30 years since graduating from The Yale School Of Drama, where he received the Carole Dye Award for Excellence in Performance, Marcus has made his living as a working actor. Over a long and accomplished career, he's done it all. Extra work. Built sets. Hung lights. Run the soundboard, and "carried furniture" in many a production. He's performed in showcases in church basements and abandoned barns with no heat. He's appeared Off Broadway in hits like Christopher Durang's "Durang! Durang!" and John Patrick Shanley's Italian American Reconciliation at such renowned institutions like the Lambs, WPA, Circle Rep and the Manhattan Theater Club. On Broadway Marcus has shared the stage with Rip Torn and Shirley Knight in Horton Foote's Tony nominated play The Young Man From Atlanta. And at Lincoln Center, he appeared alongside Campbell Scott, Kate Burton, Wayne Knight and Len Cariou in director Mark Lamos' infamous production of Measure for Measure.

Marcus worked for several years exclusively in regional theater performing the roles of Macbeth and Bottom at The Shakespeare Theater of New Jersey, Marlowe in Goldsmith's She Stoops To Conquer at the Seattle Rep, The Guthrie and at New Haven's Long Wharf Theater. His travels also took him to Hartford, Mt. Gretna, PA, Chicago and Portland Maine.

In 1987 Marcus was awarded his equity card after four seasons as a company member at the Williamstown Theater Festival where he appeared in over twenty-five productions, including the title role in the experimental theater production of Henry V, Teach in American Buffalo, and Hoss, in Sam Sheppard's Tooth of Crime. Marcus spent five seasons at the prestigious Eugene O'Neil Playwrights Conference working as an artistic consultant, and as an actor, helping writers develop film scripts, and new works for the theater under the watchful eye of Artistic Director Lloyd Richards. Marcus directed several productions at The Yale School of Drama, at The Williamstown Lab and was the original director of the Multi Media music piece Holdin' On at the Zipper Theater in New York City.

His films include work with Paul Newman in James Ivory's Mr. and Mrs. Bridge and appearances Indie hits like Judy Berlin, On The Doll, The Business of Strangers, Hamlet and The Chosen One.

His television work is vast, with appearances on a dozen Soaps, over a hundred Guest Star and Recurring roles (see resume), as well as Series Regular roles on several hit shows including Fox's Flying Blind, Showtime's dark and edgy Look, produced by Adam Rifkin, HBO's Tell Me You Love Me and the long running CBS drama Judging Amy, with Tyne Daily, Amy Brenneman and Richard Crenna.

Marcus is an accomplished professional session musician and electric bassist, playing in bands from New York City to Los Angeles, with a degree in Level 3 Jazz Bass from the Stinnett School of Music. He is also a staff feature writer for MLB Insider's Club Magazine and a contributing Freelance writer for MLB.com and most recently for Sports Illustrated.

Marcus graduated from Bowdoin College with a BA in African History and Ethnomusicology.

He is the son of former Yale President and Major League Baseball Commissioner A. Bartlett Giamatti