Reid was born in Manhattan, the son of artist Christine Challenger Reid and banker Blair Reid.
In 1935, Reid debuted on the radio program The March of Time, which led to him working regularly on radio dramas during the Golden Age of radio. Early on he took "Elliott" as his stage name. His credits include among other, many Orson Welles-directed stage and radio productions, such as The Mercury Theatre on the Air and also acted on Theatre Guild on the Air, The Adventures of Philip Marlowe, Suspense, and the CBS Radio Mystery Theater. In some early performances he was credited as "Ted Reid".
Reid's best-known film role was as Ernie Malone, private detective hired to spy on Marilyn Monroe's character, only to become Jane Russell's love interest, in the 20th Century Fox classic Gentlemen Prefer Blondes (1953). Variety praised his and Tommy Noonan's performances, saying that "Reid and Noonan carry off the romantic male spots nicely".
Reid played Professor Shelby Ashton in two Walt Disney movies starring Fred MacMurray: The Absent-Minded Professor in 1961, and sequel Son of Flubber in 1963. Reid also played Ralph Hastings in Disney's 1966 movie Follow Me, Boys!
A member of The Actors Studio from its inception, Reid was a regular in NBC television's That Was the Week That Was (1964–1965) and made guest appearances on Murder, She Wrote, The Odd Couple, I Love Lucy, Barney Miller, Small Wonder, Perry Mason, and The Munsters.
In 1992 Reid appeared in the season three Seinfeld episode "The Letter", as one of the collectors considering buying a painting of Kramer. Reid's final television role was as Henry on the episode "Please Re-Lease Me" of the television sitcom Maybe This Time. He retired in 1995, but returned for an uncredited role as Miguel in the 2000 short film Scattering Mother and the role of Buddy in the feature film adaptation of the same name in 2005.
Among his special skills, Elliot Reid was also an accomplished impressionist. He was so famous with his John F. Kennedy impersonation that, in 1962, he was invited to perform it in front of Kennedy in person; Kennedy was happy with the performance. One reference book said, "His mimicking of John F. Kennedy opened up a mini-career in clubs in the early 1960s."
Reid's Broadway credits include Julius Caesar (1937-1938), The Shoemaker's Holiday (1938), Macbeth (1948), Two Blind Mice (1949), The Live Wire (1950), Two on the Aisle (1951-1952), and From A to Z (1960).
He co-starred as Felix Unger in a road production of The Odd Couple with Dan Dailey as Oscar Madison during the late 1960s. He also appeared as an art collector in the 1992 Seinfeld episode "The Letter".
Reid died from heart failure on June 21, 2013, at the age of 93. He had resided in an assisted living facility in Studio City, California, where his nephew said he had been living for the past few years. His remains were cremated and his ashes were scattered in the Pacific Ocean.The Ramparts We Watch (1940) - Ralph Gilchrist
Young Ideas (1943) - Jeff Evans
The Story of Dr. Wassell (1944) - William 'Andy' Anderson
A Double Life (1947) - Actor in 'A Gentleman's Gentleman'
Sierra (1950) - Duke Lafferty
The Whip Hand (1951) - Matt Corbin
Gentlemen Prefer Blondes (1953) - Ernie Malone
Vicki (1953) - Steve Christopher
Woman's World (1954) - Tony Andrews
Inherit the Wind (1960) - Prosecutor Tom Davenport
The Absent-Minded Professor (1961) - Professor Shelby Ashton
Son of Flubber (1963) - Prof. Shelby Ashton
The Thrill of It All (1963) - Mike Palmer
It's a Mad, Mad, Mad, Mad World (1963) - Dr. Chadwick (voice, uncredited)
The Wheeler Dealers (1963) - Leonard
Move Over, Darling (1963) - Dr. Herman Schlick
Who's Been Sleeping in My Bed? (1963) - Tom Edwards
Follow Me, Boys! (1966) - Ralph Hastings
Blackbeard's Ghost (1968) - TV Commentator
Some Kind of a Nut (1969) - Gardner Anderson
Heaven Can Wait (1978) - Waiter (uncredited)
Young Einstein (1988) - Asylum Guard