Christopher Diamantopoulos^[1] (Greek: Χριστόφορος Διαμαντόπουλος (Khristóforos Diamantópoulos); born May 9, 1975) is a Canadian actor. He played Russ Hanneman in the HBO series Silicon Valley and starred in the film The Three Stooges, and the TV series Good Girls Revolt. He voiced Mickey Mouse in the eponymous television series, The Wonderful World of Mickey Mouse and the short film Once Upon a Studio; for the former, he received two Emmy Award nominations.^[2]

Diamantopoulos was born on May 9, 1975,^[3][4] in Toronto, Ontario, Canada. He grew up splitting his time between Canada and Greece. He is of Greek descent, his mother being from Ioannina and his father from the Peloponnese, a practicing member of the Greek Orthodox church, and a fluent Greek speaker.^[5][6]

Diamantopoulos worked on television commercials and professional theatre productions at the age of nine. By the time he turned eighteen, he left home to partake in a series of American national tours.^[7] A short time later, he worked on Broadway, where he played leading parts in The Full Monty (2002) and Les Misérables (2003).^[8] Diamantopoulos attended East York Collegiate Institute.

He played Robin Williams in Behind the Camera: The Unauthorized Story of Mork & Mindy alongside Erinn Hayes. He has guest-starred in several series, including Kevin Hill, Charmed, The Sopranos, The Office US, Nip/Tuck and Boston Legal. He played the interior decorator in the miniseries The Starter Wife.

He had a recurring role on State of Mind and guest-voiced on American Dad! in 2009.

On the eighth season of 24, he played U.S. president Allison Taylor's Chief of Staff Rob Weiss. He played Frank Sinatra in The Kennedys. Diamantopoulos played Moe Howard in the 2012 film The Three Stooges.

In 2013, Diamantopoulos voiced Mickey Mouse in Mickey Mouse, and its follow-up series The Wonderful World of Mickey Mouse. Although Bret Iwan has voiced Mickey in most media after Wayne Allwine, Diamantopoulos voiced the character in retro-styled productions, giving Mickey Mouse a voice similar to that of Walt Disney. Most recently, he reprised the character in the 2023 short film Once Upon a Studio, made to celebrate the centennial of The Walt Disney Company and Walt Disney Animation Studios.

He had recurring roles on the NBC sitcoms Up All Night, as Maya Rudolph's on and off lover, Julian; The Office, as Brian, a former member of the show's documentary film crew (alongside Zach Woods, who he would later work again with on Silicon Valley); and on Arrested Development, as Marky, Lindsay's face-blind environmentalist boyfriend.

He appeared in the television sitcom Episodes playing the part of TV network boss Castor Sotto, and Mr. Chris in the television adaptation of About a Boy.

In 2017, Diamantopoulos starred in the musical Waitress on Broadway.

On October 11, 2018, it was revealed by TVLine that he would have a role in the spin-off pilot for the situation comedy The Middle playing Sue Heck's mercurial, charming and rich boss Nick.^[9]

Diamantopoulos voiced Frank Heffley in the 2021 animated film Diary of a Wimpy Kid, released on Disney+.^[10]

He has an upcoming starring role alongside Tom Blyth in the comedy Discussion Materials^[11] adapted from Bill Keenan's memoir of the same name.

He met Becki Newton at a subway station in New York City. They married in 2005.^[12] Newton gave birth to their first child, a boy, in November 2010.^[13] In 2014, they had a girl.^[14] In 2020, they had another girl.