[3] O'Herlihy's best-known roles included his Oscar-nominated portrayal of the lead character in Luis Buñuel's Robinson Crusoe (1954),[4] Brigadier General Warren A.

Black in Fail Safe (1964), Marshal Ney in Waterloo (1970), Conal Cochran in Halloween III: Season of the Witch (1982), Grig in The Last Starfighter (1984), "The Old Man" in RoboCop (1987) and its 1990 sequel, and Andrew Packard in the television series Twin Peaks (1990–91).

[3] O'Herlihy's first notable acting role came in 1944, when he played the lead in the Gate's production of Red Roses For Me, written and directed by Seán O'Casey.

His career took an upward turn in 1954 when he played the title role in Luis Buñuel's Robinson Crusoe, which earned him an Academy Award nomination for Best Actor.

The following year he played Sir Harry Ivers, an upper-class English drifter who joins Alan Ladd in a plot to ruin an Arizona cattle town by robbing its bank, in the western One Foot in Hell.

In 1982, he starred in Halloween III: Season of the Witch as Conal Cochran and in 1984, he appeared in The Last Starfighter as Grig, Alex Rogan's reptilian co-pilot, navigator and sidekick.

O'Herlihy had a fairly extensive career in television, having appeared on Rawhide, The DuPont Show with June Allyson, Adventures in Paradise and Target: The Corruptors!.

On The Long, Hot Summer, O'Herlihy became the lead star, having replaced Edmond O'Brien in the part of Will Varner midway through the program's single-season run.

O'Herlihy also portrayed the ill-fated lumber tycoon Andrew Packard in the cult television program Twin Peaks (1991) and in the Batman: The Animated Series episode "Deep Freeze", voicing the villainous theme park mogul Grant Walker.