Family spokesman Eddy Friedfeld said Caesar, who also played Coach Calhoun in the 1978 movie Grease, died at his home in Los Angeles after a brief illness.
"He had not been well for a while. He was getting weak," said Mr Friedfeld, of New York, who wrote the 2003 biography Caesar's Hour.
Carl Reiner, who worked as a writer-performer with Caesar on his breakthrough Your Show Of Shows sketch programme, said: "Sid Caesar set the template for everybody. He was without a doubt, inarguably, the greatest sketch comedian-monologist that television ever produced. He could ad-lib. He could do anything that was necessary to make an audience laugh."
In his two most important shows, Your Show Of Shows, from 1950-54, and Caesar's Hour from 1954-57, Caesar displayed remarkable skill in pantomime, satire, mimicry, dialect and sketch comedy. He also gathered a stable of young writers who went on to worldwide fame in their own right - including Neil Simon and Woody Allen.
"He was one of the truly great comedians of my time and one of the finest privileges I've had in my entire career was that I was able to work for him," Allen said.
While best known for his TV shows, which have been revived on DVD in recent years, he also had success on Broadway and occasional film appearances, notably in It's A Mad Mad Mad Mad World.
If the typical funnyman was tubby, or short and scrawny, Caesar was tall and powerful, with a clown's loose limbs and rubbery face and a trademark mole on his left cheek. But he never went in for clowning or jokes, insisting that the laughs come from the everyday.
"Real life is the true comedy," he said in 2001. "Then everybody knows what you're talking about."
In one celebrated TV routine, he impersonated a gumball machine; in another, a baby; in another, a ludicrously overemotional guest on a parody of This Is Your Life.
The son of Jewish immigrants, Caesar was a wizard at spouting melting-pot gibberish that parodied German, Russian, French and other languages. His Professor was the epitome of goofy Germanic scholarship.
Some compared him to Charlie Chaplin for his success at combining humour with touches of pathos.
Caesar performed with such talents as Howard Morris and Nanette Fabray, but his most celebrated collaborator was the brilliant Coca, his Your Show of Shows co-star.
Coca and Caesar performed skits that satirised the everyday - marital spats, inane advertising, strangers meeting and speaking in cliches, a parody of the Western Shane in which the hero was "Strange". They staged a water-logged spoof of the love scene in From Here To Eternity and The Hickenloopers husband-and-wife skits became a staple.
"The chemistry was perfect, that's all," Coca, who died in 2001, once said. "We never went out together; we never see each other socially. But for years we worked together from 10 in the morning to six or seven at night every day of the week. What made it work is that we found the same things funny."
Caesar worked closely with his writing staff as they found inspiration in silent movies, foreign films and the absurdities of 50s post-war prosperity.
Among those who wrote for Caesar were Mel Brooks, Larry Gelbart, Neil Simon and his brother Danny, and Allen, who was providing gags to Caesar and other entertainers while still in his teens.
In 1962, Caesar starred on Broadway in the musical Little Me, written by Simon, and was nominated for a Tony. He played seven different roles, from a comically perfect young man to a tyrannical movie director to a prince of an impoverished European kingdom.
He was one of the galaxy of stars who raced to find buried treasure in the 1963 comic epic It's A Mad Mad Mad Mad World, and in 1976 put his pantomime skills to work in Brooks' Silent Movie.
But he later looked back on those years as painful ones. He said he beat a severe, decades-long barbiturate and alcohol habit in 1978, when he was so low he considered suicide.
"I had to come to terms with myself. 'Yes or no? Do you want to live or die?'" Deciding that he wanted to live, he recalled, was "the first step on a long journey".
Caesar was born in 1922 in Yonkers, New York, the third son of an Austrian-born restaurant owner and his Russian-born wife. His first dream was to become a musician and he played saxophone in bands in his teens.
But as a youngster waiting tables at his father's luncheonette, he liked to observe as well as serve the diverse clientele, and recognise the humour happening before his eyes.
His talent for comedy was discovered when he was serving in the US Coast Guard during the Second World War and got a part in a coastguard musical, Tars And Spars. He also appeared in the movie version.
That led to a few other film roles, nightclub engagements, and then his breakthrough hit, a 1948 Broadway revue called Make Mine Manhattan.
It took decades for Caesar to hit rock bottom. In 1977 he was on stage in Regina, Canada, when suddenly, his mind went blank. He walked off stage, checked into a hospital and underwent cold turkey.
His wife Florence was by his side for more than 60 years and helped him weather his demons.