Carlin, 71, died of heart failure after being taken to St. John's Health Center in Santa Monica on Sunday evening. The comedian, who had a history of heart problems, complained of chest pains, said his publicist Jeff Abraham.
"He was a genius, and I will miss him dearly," Jack Burns, who was the other half of a comedy duo with Carlin in the early 1960s, told The Associated Press.
Carlin came from the universe that included Lenny Bruce and Richard Pryor, comedians who used profanity to turn politics inside out. For them, words were meant to draw blood from the powerful while shocking the comfortable out of their routine lives.
In the process, Carlin changed comedy and influenced a new generation, Ben Stiller told the Associated Press.
"He had an amazing mind, and his humor was brave and always challenging us to look at ourselves and question our belief systems, while being incredibly entertaining. He was one of the greats," Stiller said.
"Nobody was funnier than George Carlin," said Judd Apatow, director of recent hit comedies such as "Knocked Up" and "The 40-Year-Old Virgin." "I spent half my childhood in my room listening to his records, experiencing pure joy. And he was as kind as he was funny."
"Not only did I grow up listening to and laughing at the brilliant George Carlin, but I also had the distinct pleasure of opening for him during the entire summer of 1987, when I was just breaking through in comedy," said comic Judy Tenuta.
"After our show in New York City, he was the first to call and congratulate me on the positive review my HBO special had just received. Can you imagine receiving accolades from the comedy legend, George Carlin? I will never forget that, nor this comic genius who so profoundly influenced me and every comic working today. The world has lost the Picasso of modern stand-up comedy, George Carlin."
The comedian, who toured college campuses for years and made a name for himself using dirty language and delivering biting social commentaries, had released 22 solo albums and three bestselling books.
He finished a show at the Orleans casino in Las Vegas last week and was planning to take the month off to relax and work on a new book of essays and musings, Abraham said.
Carlin normally took summers off and was scheduled to tour again beginning with a July 20 performance at Humphrey's Concerts by the Bay in San Diego. He had dates lined up through December, Abraham said.
"He was looking forward to it."
Carlin went to the hospital Sunday afternoon because "his heart just didn't feel right," the publicist said.
Carlin starred in a variety of TV and movie roles. Later in life, the scatological comedian charmed children in such shows as "Shining Time Station" and "Thomas the Tank Engine & Friends."
But he will always be remembered for his routine about the seven dirty words that could not be uttered on television.
"There are three ingredients in my comedy," he said in a 1991 interview with the Los Angeles Times. "Those three things which wax and wane in importance are English language and wordplay; secondly, mundane, everyday observational comedy -- dogs, cats and all that stuff; and thirdly, sociopolitical attitude comedy."
He earned several gold comedy albums and five Emmy nominations.
Carlin was arrested in 1972 in Milwaukee for using indecent language. In a separate case in 1973, a radio listener complained after a station played part of his album. That case went the Supreme Court, which in 1978 ruled in favor of the FCC, saying the radio station could not broadcast those words at times when children could be listening.