[1] Marcellino was born in Quincy, Massachusetts, and raised in Braintree,[2] the fifth of six children.

He was also an all conference and all state football player at Archbishop Williams High School in Braintree.

Marcellino's acting credits include television's Veronica Mars, NYPD Blue, Ally McBeal, The Tiger Woods Story, Herman's Head, Good Advice, 18 Wheels of Justice, The Invisible Man, Amazing Stories, and It's Garry Shandling's Show.

He also acted in the films Rain Man, National Security and Hot to Trot.

Marcellino has also written and performed songs for the films Rain Man, That's Life and Night of the Comet; and television shows Law & Order: Special Victims Unit, The Office, Terriers, Castle, Kath & Kim, Parks and Recreation, Golden Boy, Once Upon a Time and ESPN's Monday Countdown.