Derrick O'Connor (3 January 1941 – 29 June 2018) was an Irish character actor.

O'Connor was best known for his performance as Pieter Vorstedt in Lethal Weapon 2 and for his roles in three Terry Gilliam films. He starred as Jack Stone in The Professionals episode "You'll be Alright". He was a member of the Royal Shakespeare Company 

Gilliam, who directed O'Connor in three films, had noted in his audio commentaries that O'Connor seemed to have a habit of relinquishing most of his dialogue in favour of physical character humor. Notable examples include Time Bandits, in which his character's dialogue was resorted to simple grunts while the Maid Marian character "translated" for him and in Brazil, in which O'Connor scrapped all of his character's dialogue and simply repeated the dialogue of Bob Hoskins' character.

He died on 29 June 2018 of pneumonia in Santa Barbara, California at the age of 77. 

Select filmography

• The Final Programme (1973) as Frank
• Butley (1974) as Irishman in pub
• Jabberwocky (1977) as Flying Hogfish Peasant
• Sweeney 2 (1978) as Llewelyn
• Bloody Kids (1980) as Detective Ritchie
• Hawk the Slayer (1980) as Ralf
• Time Bandits (1981) as Robber Leader
• The Missionary (1982) as Gym Trainer
• Pope John Paul II (1984) as Swiacki
• Brazil (1985) as Dowser
• Hope and Glory (1987) as Mac
• Lethal Weapon 2 (1989) as Pieter 'Adolph' Vorstedt
• Dealers (1989) as Robby Barrell
• Stark (1993) as Zimmerman
• Felidae (1994) as Mendel (English dub)
• Ghosts (1995) as Jack Rudkin
• How to Make an American Quilt (1995) as Dean Reed
• Deep Rising (1998) as Captain Atherton
• End of Days (1999) as Thomas Aquinas
• Daredevil (2003) as Father Everett
• Pirates of the Caribbean: Dead Man's Chest (2006) as Very Old Man
• Unrest (2006) as Walter Blackwell
• The Blue Hour (2007) as Humphrey