Malcolm McDowell (born Malcolm John Taylor; 13 June 1943) is an English actor. He first became known for portraying Mick Travis in Lindsay Anderson's if.... (1968), a role he later reprised in O Lucky Man! (1973) and Britannia Hospital (1982). His performance in if.... prompted Stanley Kubrick to cast him as Alex in A Clockwork Orange (1971), the role for which McDowell became best known.

His other notable film credits include The Raging Moon (1971), Voyage of the Damned (1976), Time After Time (1979), Caligula (1979), Cat People (1982), Blue Thunder (1983), The Caller (1987), Star Trek Generations (1994), Tank Girl (1995), Mr. Magoo (1997), I'll Sleep When I'm Dead (2003), The Company (2003), Evilenko (2004), The Artist (2011), and Bombshell (2019). He also played Dr. Samuel Loomis in the 2007 remake of Halloween and its sequel, Halloween II (2009).

On television, McDowell appeared as Dornford Yates's gentleman hero Richard Chandos in the 1978 BBC adaptation of She Fell Among Thieves. He had recurring roles on Entourage (2005–2011) and Heroes (2006–2007), starring roles on Franklin & Bash (2011–2014) and Mozart in the Jungle (2014–2018), and has played Patrick "Pop" Critch on the Canadian series Son of a Critch since 2022. He has also voiced characters in various animated shows, films and video games, including Metallo on Superman: The Animated Series and Justice League Unlimited, Vater Orlaag in Metalocalypse, Dr. Calico in Bolt, President Eden in Fallout 3, Molag Bal in The Elder Scrolls Online, and Dr. Monty in Call of Duty: Black Ops III.

McDowell is the recipient of an Evening Standard British Film Award, alongside nominations for Golden Globe and Screen Actors Guild Awards. He received a star on the Hollywood Walk of Fame in 2012.