In which film did Robin Williams win his only Academy Award?

Robin McLaurin Williams (July 21, 1951 – August 11, 2014) was an American actor and comedian. Born in Chicago, Williams began performing stand-up comedy in San Francisco and Los Angeles during the mid-1970s, After rising to fame playing the alien Mork in the sitcom Mork & Mindy, Williams established a career in both stand-up comedy and feature film acting. He was known for his improvisation skills and the wide variety of memorable character voices he created. Many critics have lauded Williams as one of the funniest comedians of all time.

Williams was nominated four times for Academy Awards, winning Best Supporting Actor for his performance as psychologist Sean Maguire in "Good Will Hunting". He also received two Primetime Emmy Awards, six Golden Globe Awards, two Screen Actors Guild Awards, and four Grammy Awards.

Williams was nominated for three Best Actor Awards for: "Good Morning, Vietnam" (1988), "Dead Poets Society" (1990) and "The Fisher King" (1992).

"Good Will Hunting" is a 1997 American drama film directed by Gus Van Sant, and starring Robin Williams, Matt Damon, Ben Affleck, Minnie Driver, and Stellan Skarsgård. Written by Affleck and Damon, the film follows 20-year-old South Boston janitor Will Hunting, an unrecognized genius who, as part of a deferred prosecution agreement after assaulting a police officer, becomes a client of a therapist and studies advanced mathematics with a renowned professor.