On television, McDowell appeared as Dornford Yates's gentleman hero Richard Chandos in the 1978 BBC adaptation of She Fell Among Thieves.

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.

They then moved to Liverpool, where McDowell grew up and as a teenager took a job in a Planters nut factory in nearby Aintree, as well as working at his father's pub, The Bull and Dog, in Burscough, Lancashire.

His performance in if.... caught the attention of Stanley Kubrick, who cast McDowell for the lead in A Clockwork Orange (1971), adapted from the novel by Anthony Burgess.

He gained massive acclaim for his performance as Alex DeLarge, a young, antisocial hoodlum who undergoes brainwashing by the British government in a near future society.

He starred in Aces High (1976) and co-starred in Voyage of the Damned (1976), and as Dornford Yates' gentleman hero Richard Chandos in She Fell Among Thieves (1978) and the title character in Caligula (1979).

[10] In his biography Anthony Burgess: A Life, author Roger Lewis commented on McDowell's later career: "his pretty-boy looks faded and he was condemned to playing villains in straight-to-video films that turn up on Channel 5".

McDowell appeared in a 2000 episode of the animated series South Park, which was a comedic retelling of the Charles Dickens novel Great Expectations.

In the episode, McDowell played the real-life narrator of the story in live action, introducing himself simply as "a British person", in a parody of Masterpiece Theatre, and its ex-host, Alistair Cooke.

[12] McDowell played himself in Robert Altman's The Player, in which he chastises protagonist Griffin Mill (Tim Robbins) for badmouthing him behind his back.

In the film I'll Sleep When I'm Dead (2003), he played a straight married man who rapes a young drug dealer to "teach him a lesson".

[17][18] He also played Desmond LaRochette in Robert Whitlow's The List (2007), and Irish patriarch Enda Doyle in Red Roses and Petrol (2003).

[22] In 2011, McDowell was cast in the role of Stanton Infeld on the TNT original series Franklin & Bash and appeared in the Academy Award-winning film The Artist.

[23] In 2013, McDowell also ventured into the Steampunk genre, starring in the short film Cowboys & Engines alongside Richard Hatch and Walter Koenig.

[24][25] McDowell also played Boogeyman in Abnormal Attraction (2018) co-starring Gilbert Gottfried, Bruce Davison, Tyler Mane and Leslie Easterbrook.

He voiced Lord Maliss in Happily Ever After (1989), Zarm in the cartoon Captain Planet and the Planeteers, the Superman villain Metallo in Superman: The Animated Series, Mad Mod on Teen Titans, Merlyn in DC Showcase: Green Arrow (2010), Arkady Duvall (son of Ra's al Ghul) on Batman: The Animated Series and as the voice of a Death Star commander on a Robot Chicken episode parodying Star Wars.

McDowell also voiced Dr. Calico in Disney's Bolt (2008) and the henchman Reeses II in the animated series Captain Simian & the Space Monkeys, a show laced with references to many films, including his own role in A Clockwork Orange.

[citation needed] In 2006–07, he contributed spoken word to two Pink Floyd tribute albums produced by Billy Sherwood: Back Against the Wall and Return to the Dark Side of the Moon.

[citation needed] McDowell reprised his role of Metallo in the video game Superman: Shadow of Apokolips and an episode of Justice League Unlimited.

McDowell is the host of Fangoria's Dreadtime Stories, a monthly series of radio dramas with a mystery, horror, science fiction and dark humour theme.