Wasserman died Sunday of congestive heart failure at his home in Paradise Valley, Ariz., said Richard Warren, a friend.
Beginning with writing live television dramas in the 1950s, Wasserman went on to write screenplays for several films, including "The Vikings" (1958), starring Kirk Douglas; and "Mister Buddwing" (1966), starring James Garner.
But it was as one of America's most-produced living playwrights, thanks largely to "Man of La Mancha," that he was best known over the last four decades.
"Man of La Mancha," with music by Mitch Leigh and lyrics by Joe Darion, opened in 1965 and closed in 1971 after more than 2,300 performances in four different New York theaters.
The musical -- based on the life of Spanish novelist and playwright Miguel de Cervantes and Cervantes' famous literary creation Don Quixote -- won five Tony Awards, including best musical, best composer and lyricist, and best actor in a musical (for Richard Kiley).
In 1997, Wasserman told the Seattle Post-Intelligencer that "Man of La Mancha" had been translated into at least 40 languages and "there are always between 40 and 50 productions going on at any given moment."
The musical, Wasserman told The Times in 1994, "speaks across borders well, without any references to political situations -- it's about as close to universal as one can get. I didn't know when I was writing it, of course."
The genesis of "Man of La Mancha" was Wasserman's "I, Don Quixote," a 90-minute 1959 television drama on "The Du Pont Show of the Month," starring Lee J. Cobb as both Cervantes and Don Quixote and Eli Wallach as Sancho Panza.
Wasserman was living in Spain and working on a film script when he decided to write the TV play.
"An article in the International Herald-Tribune said, erroneously, that I was in the country writing a new adaptation of 'Don Quixote,' " he recalled in the 1994 interview with The Times.
"As it happened, I'd never read the novel. I still haven't, all the way through. As a matter of fact, I don't really like the novel."
But, he said, he noticed that "there have been over 400 adaptations of 'Don Quixote,' and they've all failed. I began researching it, and the thing that interested me was the character of Cervantes, not Don Quixote."
As Wasserman said of Cervantes in a 1959 interview with The Times, "Here, surely, was one of the unluckiest men who ever lived. Dogged by poverty, pursued by misfortune, his life was a saga of failure . . . five times in prison, twice excommunicated by the church, often near starvation, he bore the hardships with good humor and unflagging faith in life."
Cervantes was in his 50s and imprisoned when he began writing his literary classic.
In building his teleplay around Cervantes, Wasserman said he decided to "express his spirit in the terms of the literary characters he created -- his courage, his humor and his belief in illusion as the bread of life."
If he were to define his teleplay in one sentence, Wasserman said, it would be in the creed he wrote for Quixote to say:
"To dream the impossible dream, to fight the unbeatable foe, and never to stop dreaming or fighting -- this is man's privilege and the only life worth living."
Wasserman's stage adaptation of "One Flew Over the Cuckoo's Nest," Kesey's 1962 novel set in a mental hospital, starred Kirk Douglas as the rebellious Randall P. McMurphy. The drama opened on Broadway in 1963 and closed after 82 performances.