Born in Dundee, Scotland, Cox was the youngest of five and was raised primarily by his older sisters and aunt, following his father's untimely death and his mother's subsequent mental breakdowns. In school, he developed a reputation as the class clown, though in reality he was troubled by his home life and barely achieved passing grades. Fortunately, he discovered the Dundee Repertory Theatre when he was 14, and "knew I belonged there from day one." Cox made his debut with the local theater in "Dover Road," and spent the next several years there, honing his craft, before he was accepted into the London Academy of Music and Dramatic Art. In 1967, Cox made his London stage debut in a Birmingham Repertory Theatre production of "As You Like It." While he played Russian revolutionary Leon Trotsky in the epic feature "Nicholas and Alexandra" (1971), Cox concentrated on his London stage career over the next decade and a half, working on a dizzying number of productions a year, including "Peer Gynt" and "Danton's Death" and earning a reputation for his starring roles in "Julius Caesar" and "Macbeth."After an acclaimed performance as King Henry II of England in the serial "The Devil's Crown" (BBC2, 1978), Cox began to transition into steady screen work with guest appearances on special television events like the Masterpiece Theatre production "Therese Raquin" (PBS, 1981) and the CBS TV movie, "The Pope" (1984). The following year he made his Broadway debut playing the doctor who helps the heroine have a child in Eugene O'Neill's "Strange Interlude." His success in the role led to more work in American-produced TV movies and a brief flirtation with Hollywood in a turn as Dr. Hannibal Leckter in Michael Mann's, "Manhunter" (1986), some five years prior to Anthony Hopkins' Oscar-winning version of the criminal mastermind in "The Silence of the Lambs" (1991). While many ultimately found Cox's take on the character far scarier and better-acted than Hopkins', the film was a box office flop at the time. The deflated Scotsman returned to London, where he joined the prestigious Royal Shakespeare Company and garnered some of the best reviews of his career (as well as an Olivier Award) for playing Shakespeare's "Titus Andronicus" (1988). Two years later, he set tongues wagging again with his searing ''King Lear."Following his theatrical triumphs, Cox returned to the screen to deliver a complex, layered portrayal of a closeted homosexual struggling with the discovery that his son is also gay in the British TV movie "The Lost Language of Cranes" (1991), for which he was recognized with a Best Actor nomination from the BAFTA Awards. That same year, Cox also starred as a wealthy eccentric who has his former wife duplicated in a laboratory in "The Cloning of Joanna May" for Granada Television. On a television roll, Cox next portrayed the Irish mentor of a British rifleman in the first two installments of "Sharpe" (1993), which aired on PBS' "Masterpiece Theater" in the states. Then, at nearly the age of 50, the well-respected actor thought he would see what sort of acting opportunities he might find in films, feeling that he was treading the same territories repeatedly. After establishing himself with a memorable role as Mel Gibson's brother in the Oscar-winning "Braveheart" (1995), Cox's Hollywood career accelerated with a pivotal role in another historical epic, "Rob Roy" (1995), in which he played a snitch whose information leads to the death of a kinsman of the title character. He was rapidly cast in a succession of bad-guy roles in middling thrillers "The Long Kiss Goodnight" (1996) and "The Glimmer Man" (1996), and made a strong impression in his role as an IRA leader in Jim Sheridan's Golden Globe-nominated drama, "The Boxer" (1997), starring Daniel Day-Lewis.On the New York stage, Cox triumphed in Conor McPherson's one-man drama "St Nicholas" (1997) - after performing the play 40 times in London - and went on to succeed Alan Alda in the Tony-winning play "Art" on Broadway. In a pair of excellent American indie film appearances, Cox was memorable as the irascible headmaster of a boys' prep school in Wes Anderson's "Rushmore" (1998) and gave a touching performance as a self-destructive alcoholic who unwittingly befriends a serial killer in "The Minus Man" (1999). Cox played Mark Wahlberg's Irish cop father in the considerably higher profile offering, "The Corrupter" (1999), and continued to build his Hollywood resume playing a baseball team owner looking to sell his flagging franchise in the Kevin Costner vehicle, "For Love of the Game" (2000). Cox shone as Lord Morton in the acclaimed TV drama "Longitude" (A&E, 2000) and elevated the mediocre serial killer drama "Complicity" (2000). Perhaps his best performance of that year was his turn as Nazi leader Hermann Goering in the TNT original film "Nuremberg," for which he won an Emmy and earned Golden Globe and Screen Actors Guild award nominations. The following year, Cox was featured in two Sundance Film Festival offerings beginning with "L.I.E." (2001), earning an Independent Spirit Award nomination for his complex portrayal of an ex-marine and pederast who befriends a troubled teen (Paul Dano). He followed up with a comedic performance as a hard-nosed, small town police captain in the cult favorite "SuperTroopers" (2001), earning kudos for delivering two engaging and worlds-apart performances.While 2001 was the busiest year of Cox's film career up until that time, with further supporting roles in the Scottish gangster drama "Strictly Sinatra" and the period drama, "The Affair of the Necklace," the actor's momentum hit a frenzied peak in 2002. He appeared in the well-received indie British drama "The Reckoning" and had a high-profile role of a CIA chief attempting to cover his tracks in the Matt Damon spy blockbuster "The Bourne Identity," based on the best-selling Robert Ludlum novel. In another of that year's blockbusters, Cox appeared in the horror film "The Ring" (2002), as well as played the estranged military father of an aspiring middle-aged Texas baseball player (Dennis Quaid) in "The Rookie" (2002). Always in demand in the independent film world, Cox portrayed real-life screenwriting guru Robert McKee in Spike Jonze's "Adaptation" (2002) and donned a New York accent to play the father of a convicted drug dealer in Spike Lee's ''25th Hour'' (2002). In a rare American television guest spot, Cox also received an Emmy nomination that year for playing the besotted father of Daphne Moon (Jane Leeves) on the hit sitcom "Frasier" (NBC, 1993-2004). In one of Cox's most visible and commercial roles, he played the X-Men's villainous anti-mutant adversary Stryker in director Bryan Singer's big-budget sequel, "X2: X-Men United" (2003) and followed up with the considerably lesser-seen British medieval mystery, "The Reckoning" (2003). After reprising his role in the 2004 blockbuster sequel "The Bourne Supremacy" (2004), Cox took on the historic role of King Agamemnon in "Troy" (2004), Wolfgang Petersen's epic, action-oriented adaptation of Homer's tale of the Trojan War, in which he delivered a rare scenery-chewing performance. He cut a more subdued figure in his brief supporting role in the Wes Craven-directed thriller "Red Eye" (2005), and after a small role in the tasteless Johnny Knoxville vehicle "The Ringer" (2005), Cox was tapped by Woody Allen for the filmmaker's acclaimed return to form, "Match Point" (2005). Atypically reserved in his performance, Cox played the rich, but charitable father-in-law of an ex-tennis pro (Jonathan Rhys-Meyers) who embarks upon a complicated love affair with a struggling American actress (Scarlett Johansson). Leaving the horror and broad comedy of 2005 behind him, Cox stayed close to critically-praised projects with the adaptation of Augusten Burroughs' best-selling memoir, "Running With Scissors" (2006), playing an unorthodox psychiatrist who cares for the bipolar mother of a young boy (Joseph Cross). He then joined the cast of HBO's award-winning revisionist Western, "Deadwood" (2004-) as Jack Langrishe, an eccentric theater owner who tries to bring art and culture to the lawless town. Cox made for an exuberant presence in the violent western town and his exchanges with old pal Al Swearengen (Ian McShane) were a high point of the underrated third season. However around this time, "Deadwood" was unceremoniously axed from HBO's schedule.Cox returned to theaters with a co-starring role in "Zodiac" (2007), David Fincher's take on the search for the famed Zodiac Killer who was credited with five grisly murders in the Bay Area during the late-1960s. Following his portrayal of a lawyer involved in the case, Cox made his mark on Broadway again in Tom Stoppard's Tony-winning play "Rock 'n' Roll." Cox next enjoyed prominent roles in a number of festival-only releases, including "The Flying Scotsman" (2007) and "The Escapist" (2008), which earned him a BAFTA Scotland Award for Best Acting Performance in a Film. In a rare starring role, he gave an understated and powerful performance as a quiet, rural man who wages an all-out battle for justice against a group of juvenile delinquents in "Red" (2008). The same year, he reunited with Ian McShane in the primetime series "Kings" (NBC, 2009), a modern-day take on the story of King David in which the duo were well-matched as rival kings.