Recently, Platt starred alongside Heath Ledger and Sienna Miller in Lasse Hallstrom's "Casanova." Platt plays Papprizzio, a loveable lard merchant betrothed to Sienna Miller's character.
Platt was also seen in the Harold Ramis film "Ice Harvest," in which he appeared opposite John Cusack and Billy Bob Thornton. He also teamed with Cusack again on the feature "Martian Child."
Other film credits include "Funnybones," "Bulworth," "Married to the Mob," "Working Girl," "Flatliners," "Indecent Proposal," "The Three Musketeers," "A Time to Kill," "Doctor Dolittle," "Simon Birch," "Don't Say a Word" and "Pieces of April."
In April 2006, Platt made his Broadway debut in "Shining City" and earned a Tony nomination.
Platt made his producing debut on the indie film "Big Night," which was co-directed by actors Stanley Tucci and Campbell Scott. He would later re-team with Tucci in "The Imposters."
On television, Oliver received an Emmy nomination for outstanding guest actor in a drama series for his role as White House Counsel Oliver Babish on the popular political drama "The West Wing."
Platt graduated from Tufts University with a degree in drama and immediately began working in regional theater, as well as off-Broadway, in such productions as "The Tempest," and John Guare's "Moon Over Miami."
The son of a career diplomat, Platt was born in Washington, D.C., and spent part of his childhood in Asia and the Middle East.
Platt resides in New York with his wife and three children.