A son-in-law, Donald Saunders, said Mr. Robertson died at Stony Brook University Medical Center a day after his birthday.
His long movie career began with 'Picnic' in 1955 and continued through 'Spider-Man' and its two sequels in the 21st century. Also a familiar face in television dramas from the earliest days of the medium, he was consistently praised by critics, but never quite reached the top echelon of movie stardom.
Mr. Robertson, a frequent critic of the movie industry who once said he went to Hollywood only to work and never to live, blew the whistle on David Begelman, the president of Columbia Pictures, in 1977 after he discovered that Mr. Begelman had forged his name to a $10,000 studio check. Mr. Begelman was subsequently accused of embezzling more than $61,000 from the studio.
He pressed his complaint against the advice of many in Hollywood who did not want Mr. Begelman to become a liability to the movie industry. Mr. Begelman pleaded no contest to charges of grand theft and was fined $5,000 and sentenced to three years' probation. He was first suspended and then fired. His legal problems notwithstanding, he was hired to run Metro-Goldwyn-Mayer in 1980.
Mr. Robertson, on the other hand, temporarily became a nonperson in Hollywood — essentially blacklisted, he said, by forces within his own industry.
'People told me I set a dangerous precedent,' he said in 1994. 'My ex-wife said that if I had played the game I would have owned the town, but I was always too independent.'
Mr. Robertson eventually found his way back into Hollywood's good graces, probably because his talent was impossible to ignore. An actor who was often more compelling than the movies he made, he won the Academy Award in 1969 for his performance in one of the better ones, 'Charly,' in which he played a lovable bakery worker with the I.Q. of a 5-year-old whose intelligence is raised to genius level by an experiment, only to inexorably regress to what it had been.
'Charly' was a hit. Mr. Robertson's directorial debut, 'J. W. Coop' (1972), in which he played an aging rodeo performer who regains his freedom after spending almost a decade in jail for writing a bad check and assaulting a sheriff, was not. But like 'Charly,' it was a labor of love — Mr. Robertson also had a hand in writing the screenplay — and like 'Charly,' it was widely praised.
While he worked on that film, he said in a 1972 interview, he turned down lucrative offers for others, including 'Dirty Harry.' He was already almost as well known for the movies he did not make as for the ones he did. He starred in 'Days of Wine and Roses' on television, but Jack Lemmon starred in the movie. And when Tennessee Williams's 'Orpheus Descending,' in which he had appeared on Broadway, was made into the movie 'The Fugitive Kind,' his part was played by Marlon Brando.
Of the movie roles he did play, he told The New York Times in 1972, 'Nobody made more mediocre films than I did.' His early credits included forgettable entries like 'Autumn Leaves' (1956), a vehicle for Joan Crawford; 'Gidget,' the original teenage surfing movie (1959); and 'Sunday in New York' (1963), in which Peter Nero's theme song was quite possibly more memorable than the script.
He also starred in numerous war movies — including, memorably, 'PT 109' (1963), in which he played John F. Kennedy, and, less memorably, 'Too Late the Hero' (1970), which he described as 'a bunch of junk.'
He earned good reviews when he had good scripts, as he did in the political drama 'The Best Man' (1964), written by Gore Vidal and based on his play. In the 1975 film 'Three Days of the Condor' he played another sinister figure — an amoral finagler for a federal spy agency — and got more good notices.
Clifford Parker Robertson III was born on Sept. 9, 1923, in La Jolla, Calif., the son of Clifford Parker Robertson II, the idle heir to a tidy sum of ranching money, and the former Audrey Winningham. His parents were divorced when he was a year old, and his mother died when he was 2. He was never close to his father and was raised by his maternal grandmother and an aunt.
In high school he acted in student plays, mostly to avoid classes that bored him. After serving in the merchant marine, he went to Antioch College in Ohio. He became interested in journalism there and worked briefly for a local newspaper and radio station, but the dean encouraged him to pursue acting.
He left Antioch without getting a degree and moved to New York, where he studied at the Actors Studio. His presence and his soft sandpaper voice soon won him roles: he appeared in a production of 'Three Men on a Horse' that made the rounds of Catskill hotels, toured with the national company of 'Mr. Roberts' and made his Broadway debut in 1953 in the play 'Late Love.'
His film debut came two years later, shortly after he appeared onstage with Helen Hayes in Joshua Logan's play 'The Wisteria Trees,' when Mr. Logan cast him in 'Picnic.' But in those years, Mr. Robertson was primarily a television actor. He appeared on 'The United States Steel Hour,' 'The Chrysler Theater,' 'Playhouse 90' and other mainstays of quality repertory programming in what came to be called television's golden age. He won an Emmy in 1966 for a 'Chrysler Theater' performance.
He returned to series television as a regular on 'Falcon Crest' in the 1983-84 season and played Henry Ford in the 1987 miniseries 'Ford: The Man and the Machine.' His later movies included 'Wild Hearts Can't Be Broken' (1991), 'Renaissance Man' (1994) and 'Spider-Man' and its two sequels, in which he played the title character's uncle (killed in the first movie, he was seen in flashback in the later installments). He was also a television spokesman for AT&T for 10 years.
Mr. Robertson was twice married, to the actresses Cynthia Stone and Dina Merrill. Both marriages ended in divorce. He is survived by a daughter, Stephanie Saunders of Charleston, S.C., and one grandchild. Another daughter, Heather Robertson, died in 2007. Late in life, Mr. Robertson spent several years trying in vain to get backing for a sequel to 'Charly,' going so far as to shoot 15 minutes of material on his own. 'You don't have to be a 17-year-old zealot to wage guerrilla warfare,' he told The Los Angeles Times in 1998. 'Some of us, by nature, are intrigued by the challenge.'
In that same interview, he reflected on his role in the Begelman scandal, two decades earlier. 'I never intended to play Don Quixote,' he said, 'and I don't intend to go out looking for more windmills, I can tell you. I love making movies too much.' NY Times