Matthew MacFadyen (born 1974) is a British actor, best known for his role as MI5 agent Tom Quinn in the BBC television drama series Spooks. After having studied at the Royal Academy of Dramatic Arts from 1992 to 1995, MacFadyen quickly became a well-known actor on the British stage, due primarily to his work with the stage company Cheek by Jowl, for whom he played Antonio in The Duchess of Malfi, Charles Surface in The School for Scandal, and Benedick in Much Ado About Nothing. His Benedick was particularly memorable, played as an officer-class buffoon with a moustache and a braying laugh.

MacFadyen's major TV breakthrough came when he co-starred in a television adaptation of Emily Bront맳 novel Wuthering Heights, screened on the ITV network in 1998. Further television drama work followed, including starring roles in the dramas Warriors (1999) and The Way We Live Now (2001), both for the BBC. Also in 2001, he earned much critical acclaim for his starring role in the prestige BBC Two drama serial Perfect Strangers, which was written and directed by Stephen Poliakoff.

In 2002 he took his highest-profile role to date, when he was picked to star in Spooks, which went on to become a huge popular and critical success when screen on BBC One. A longer second season was screened in 2003, and a third season is due to air in the autumn of 2004. The series has also found a following on cable television in the United States, where it airs as MI5 on the A&E Network.

MacFadyen has also appeared in several films, most notably Enigma (2001), in which he was oddly cast as a battle-scarred submarine commander. He is currently filming a starring role as Mr Darcy in a new film adaptation of Pride and Prejudice, due for release in 2005.

In 2003 he began a relationship with his Spooks co-star Keeley Hawes, and they are expecting their first child later in 2004.