Costabile was born in Washington, D.C., and is of Italian descent.[2][3] He graduated from Gonzaga College High School, a Jesuit institution, where he was active in the school’s musical theater program. He holds an undergraduate degree from Tufts University and an MFA from New York University.[4]
Costabile also appeared in season six of The Office, as a banker sent from Sabre to evaluate Dunder Mifflin, and in the House episode "Changes" as a limousine driver. During the second series of Franklin & Bash, he guest-starred as a senior partner of the Infeld Daniels New York office, investigating Franklin and Bash because of a complaint filed against them by a former client. He had a minor guest star role in a season 3 episode of The Good Wife, playing the defendant's lawyer in a lawsuit against Lockhart and Gardner, and in a two episode story arc on BBC One's Ripper Street. Costabile also played Mr. Braddock, an attorney to the primary suspect in an episode of The Closer titled "Unknown Trouble", the first episode of season 7.
He has appeared in several television commercials, including ads for Microsoft and FedEx. In 2011, he appeared in Lie to Me as Dr. Mitch Grandon, the head doctor of a psychiatric institution in the Season 3 episode "Funhouse". In 2013, he appeared inElementary as Danilo Gura, a custodian of a hospital in the Season 1 episode "Lesser Evils". Costabile appeared as Internal Affairs investigator Simon Boyd in the 2013 TV show Low Winter Sun. He appeared in Person of Interest in Season 1 as Samuel Gates.[5] He appeared in The Blacklist in Season 2 as Dr. Linus Creel. He starred in the television series Dig.
In an April 2013 article about television, Wired magazine called Costabile "a performer who inhabits his characters so perfectly as to consistently be a fan favorite" and "one of the best things about" every television show in which he has appeared.[6]