Cox was trained at the
London Academy of Music and Dramatic Art. He made his first television appearance as an extra in several episodes of
The Prisoner in 1967 before taking a lead role in
The Year of the Sex Olympics the next year. In 1978, he played King
Henry II of England in the acclaimed
BBC2 drama serial,
The Devil's Crown, following which he starred in many other television dramas. His first film appearance was as
Leon Trotsky in
Nicholas and Alexandra in 1971. During the production of
Manhunter, while he was playing Hannibal Lecter,
Anthony Hopkins was playing
King Lear on stage at the National Theatre. Years later, during the production of
The Silence of the Lambs, when Hopkins took over as Hannibal Lecter, Cox was playing King Lear at the National Theatre.
In 1995, he appeared in both
Rob Roy and
Braveheart. His notable recent films include
The Ring,
X2,
Troy and
The Bourne Supremacy. He usually plays villains, such as a rogue colonel in
X2, the tyrannical
Agamemnon in
Troy, Pariah Dark in the
Danny Phantom television movie
Reign Storm, and devious
CIA officials in the
Bourne films and
Chain Reaction. He has on occasion played more sympathetic characters, such as
Edward Norton's father in
25th Hour, a fatherly police superior in
Super Troopers,
Rachel McAdams' father in
Red Eye, and also appeared in the comedy
Frasier as
Daphne Moon's father. Cox has also been involved in the video game industry. Among his most prominent roles were
Killzone, in which he played the ruthless
Scolar Visari, and as the voice of Lionel Starkweather, a
snuff film director in
Manhunt.
Cox garnered critical acclaim for his performance in 2001's
L.I.E., in which he played a
pedophile who grows to genuinely (and platonically) care about a boy he had initially intended to
molest. He won an
Emmy Award that year for his portrayal of
Hermann Göring in the television mini-series
Nuremberg, which starred
Alec Baldwin as former
Supreme Court Justice and
Nuremberg prosecutor
Robert H. Jackson. In 2002, he appeared in
Spike Jonze's Charlie Kaufman-scripted Adaptation as the real-life screenwriting teacher,
Robert McKee, giving advice to
Nicolas Cage in both his roles, as Charlie Kaufman and Charlie's fictional twin-brother Donald. Cox was to play the lion
Aslan in
The Chronicles of Narnia: The Lion, the Witch and the Wardrobe, but was replaced by
Liam Neeson. He appeared on a 2006 episode of the British car programme
Top Gear (as a Star in a Reasonably Priced Car).
His radio work includes the BBC series
McLevy (1999-2006) , based on the real life detective
James McLevy.
Cox appeared in a supporting role as Jack Langrishe in the
HBO series
Deadwood. He is also filming
Red, based on
Jack Ketchum's novel and directed by Lucky McKee. It also stars
Tom Sizemore, Amanda Plummer, and
Angela Bettis.