James Doohan, best known for playing Montgomery "Scotty" Scott on the original Star Trek series, has died at the age of 85.

The Canadian actor died early Wednesday morning at his home in Redmond, Wash., said his agent and friend Steve Stevens. The cause of death was pneumonia and Alzheimer's disease.

Last summer, Doohan's family and representatives confirmed that the ailing actor had been diagnosed with Alzheimer's disease.

James Doohan as 'Star Trek' engineer Scotty in 1967. (Photo: Hulton Archive/Getty Images)

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Doohan had been suffering from Parkinson's disease, diabetes and lung fibrosis, which he developed after chemical exposure during the Second World War, when he served as a captain in the Royal Canadian Artillery.

In late August, Doohan was recognized with a star on the Hollywood Walk of Fame. Joined at the ceremony by three of his former Star Trek co-stars – George Takei, Nichelle Nicols and Walter Koenig – he made what was expected to be one of his last public appearances.

Doohan appears in a scene from the Arthur Hailey-penned CBC-TV drama 'Flight Into Danger,' which aired April 3, 1956. (CBC Still Photo Collection)

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Born in Vancouver in March 1920, Doohan was raised in Sarnia, Ont. After the Second World War, where he took part in the Juno Beach invasion on D-Day, Doohan became an actor, beginning on radio dramas in 1946.

He later moved into TV as a character actor, including a role on the 1953 CBC series Space Command and the 1956 CBC-TV drama Flight Into Danger, author Arthur Hailey's first screenplay. The show would serve as an inspiration for Hailey's debut novel, Runaway Zero-Eight, published in 1958, and the 1970s disaster film genre.

Doohan's ability to master many dialects and different accents impressed Gene Roddenberry, the creator of a new space adventure, in 1966. On the strength of a strong Scottish accent, producers chose Doohan for the original cast of Star Trek, which ran from 1966 to 1969.

He was eventually burned into pop culture history, with iconic Star Trek phrases like "Beam me up, Scotty." Doohan later reprised his role as the scrappy space engineer Scotty in seven Star Trek movies and a number of video game adapations.