Moore, who starred in 10 and Arthur, had been suffering from progressive supranuclear palsy, a rare degenerative brain disorder. He died of pneumonia, a complication of the condition, at 11 a.m. EST.

Moore began his career not as an actor but as a musician. Born and raised in the London suburb of Dagenham, he developed an early love for music, attending the prestigious Guildhall School of Music and later winning a scholarship to Oxford's Magdalen College. He eventually branched out, penning incidental music for plays and eventually acting on stage. After receiving two degrees, he spent the next couple of years as a working musician, playing in jazz ensembles and touring the world with the Vic Lewis Orchestra and the John Dankworth Band.

When Moore returned to England in 1960, he joined Alan Bennett, Jonathan Miller and Peter Cook to perform at the Edinburgh Festival in the revue Beyond the Fringe, a precursor of sorts to Monty Python. Their little stage show was a hit in London and Broadway, where it was honored with a Special Tony Award.

Moore and Cook went on to form a long-standing collaboration that encompassed stage, song and screen. Together they created the comic characters Dud and Pete. When Cook opted to retire early, Moore settled in Los Angeles and went on to achieve stardom in Hollywood in a series of romantic comedies.

Moore co-starred with Chevy Chase and Goldie Hawn in the 1978 comedy Foul Play, but his real breakout role came in 1979 after starring opposite Bo Derek in 10. In 1981, the British-born actor earned an Oscar nomination for his portrayal of a hard-drinking millionaire in the comedy Arthur alongside Liza Minnelli.

In the 1990s, Moore joined with conductor Sir Georg Solti to develop and co-host the acclaimed Showtime series Orchestra!. He also attempted the small screen but neither of his CBS sitcoms Dudley, or Daddy's Girls, caught on with viewers.

Around 1994, Moore began to experience health problems, becoming unsteady on his feet and suffering short-term memory loss. Rumors of drug use started to spread and Moore was fired from Barbra Streisand's film The Mirror Has Two Faces for repeatedly forgetting his lines. He was later diagnosed with the rare and devastating brain disorder progressive supranuclear palsy (PSP).

Moore went public with his condition in 1999 when his speech slurred and his walking became impaired. Moore maintained a sense of humor throughout his illness, and said in a statement:

"I understand that one person in 100,000 suffers from this disease, and I am also aware that there are 100,000 of my union, the Screen Actors Guild, who are working everyday.

"I think therefore it is in some ways considerate of me that I have taken on the disease for myself, thus protecting the remaining 99,999 SAG members from this fate."

Campaigning for a cure, Moore issued a CD of his music, Dudley Moore - Live From an Airplane Hangar in 2000, with some sale proceeds split between two charitable organizations.

In November of last year, a wheelchair-bound Moore flew from his home in New Jersey to England to collect his CBE (Commander of the British Empire) from the Prince of Wales at a ceremony at Buckingham Palace. His close musician friend Brian Dallow and his sister Barbara Stevens accompanied him on the trip.

"It's extremely frustrating for Dudley, " Dallow told the BBC. "He understands everything. It all goes in, but it's so difficult for him to respond."

Moore had been living in New Jersey with Dallow and his wife Rena Fruchter. He was undergoing physical and speech therapy at the Kessler Institute for Rehabilitation in West Orange, New Jersey.

Moore is survived by his two sons.