Matthew Avery Modine (born March 22, 1959) is an American actor and filmmaker. He shared the Venice Film Festival's Volpi Cup for Best Actor as part of the ensemble cast of Robert Altman's film Streamers (1983). He went on to play lead roles in several high-profile films throughout the 1980s, including Birdy (1984), Vision Quest (1985), and Married to the Mob (1988). He gained further prominence for playing U.S. Marine James T. "Joker" Davis in Stanley Kubrick's Full Metal Jacket (1987).

Other notable films include Pacific Heights (1990), Short Cuts (1993), Cutthroat Island (1995), The Dark Knight Rises (2012), and Oppenheimer (2023). On television, he portrayed Dr. Don Francis in the HBO film And the Band Played On (1993), Sullivan Groff on Weeds (2007), Ivan Turing in Proof (2015), and Dr. Martin Brenner on Netflix's Stranger Things (2016–2022).

Modine has been nominated twice for a Golden Globe Award for Best Actor in a Miniseries or Motion Picture Made for Television for his work in And the Band Played On and What the Deaf Man Heard and received a special Golden Globe for him and the rest of the ensemble in Short Cuts. He was also nominated for a Primetime Emmy Award for Outstanding Lead Actor in a Miniseries or a Special for And the Band Played On.