William Gaither Crudup (born July 8, 1968) is an American actor. He is a four-time Tony Award nominee, winning once for his performance in Tom Stoppard's play The Coast of Utopia in 2007. He has been nominated for an Independent Spirit Award for Best Male Lead (along with several other awards nominations) for his performance in Jesus' Son. He received two Screen Actors Guild Award nominations as part of an ensemble cast for Almost Famous and Spotlight, winning for the latter - as well as winning the Independent Spirit Robert Altman Award for the same. He earned two Primetime Emmy Awards (nominated three times); two Critics' Choice Television Awards; a nomination for Golden Globe Award for Best Supporting Actor – Series, Miniseries or Television Film; and three nominations for a Screen Actors Guild Award for Outstanding Performance by a Male Actor in a Drama Series for his performance on the series The Morning Show (2019).

He has starred in numerous high-profile films, including Without Limits, Princess Mononoke, Almost Famous, Big Fish, Mission: Impossible III, Watchmen, Public Enemies, Spotlight, Jackie, The Stanford Prison Experiment, Justice League, and Alien: Covenant, in both lead and supporting roles.

From 1996 to November 2003, he was in a relationship with actress Mary-Louise Parker. She was seven months pregnant with their son, William Atticus Parker born in January 2004, when he ended their relationship and began dating actress Claire Danes, their relationship ended in 2006.

In 2017, he began dating actress Naomi Watts, after the two met on the set of the Netflix drama series Gypsy. They married in New York City in June 2023.

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