Dennis William Quaid (born April 9, 1954) is an American actor.

After his brother, Randy, was nominated for an Academy Award for Best Supporting Actor for his role in The Last Detail (1973), Quaid dropped out of the University of Houston before graduating and moved to Los Angeles to pursue an acting career of his own. He initially had trouble finding work but began to gain notice when he appeared in Breaking Away (1979) and earned good reviews for his role in The Right Stuff (1983).

With a flair for both both comedic and dramatic roles, Quaid starred in the films Enemy Mine (1985) and Innerspace (1987). He also achieved acclaim for his portrayal of Jerry Lee Lewis in Great Balls of Fire! (1989).

Quaid's career lost steam in the early 1990s, after he fought anorexia nervosa and kicked a cocaine addiction. He continued to garner positive reviews in a variety of films, however, such as Doc Holliday in Wyatt Earp (1994). He starred in the remake of The Parent Trap (1998), playing the part of the twins' father, and as an aging pro football quarterback in Oliver Stone's Any Given Sunday (1999). Some of Quaid's more recent film credits include Frequency (2000), The Flight of the Phoenix (2004), In Good Company (2004), The Day After Tomorrow (2004), Yours, Mine and Ours (2005), Vantage Point (2008), G.I. Joe: The Rise of Cobra (2009), and Pandorum (2009).

For his role in Far From Heaven (2002), he won the New York Film Critics Circle Award for Best Supporting Actor, the Chicago Film Critics Association Award for Best Supporting Actor, the Online Film Critics Society Award for Best Supporting Actor and the Independent Spirit Award for Best Supporting Male. He received nominations for Best Supporting Actor from the Golden Globe Awards, the Phoenix Film Critics Society Awards and the Screen Actors Guild Awards.