Four-time Grammy winner comedian George Carlin died at 71 in Los Angeles. He passed away on Sunday after being admitted to St. John's Health Center, complaining of chest pain, AP reports. He died just before 6 p.m. Carlin has had several other heart attacks.

Carlin leaves behind not only a legendary comedic legacy (he left behind 23 comedy albums, 14 HBO specials, three books, a couple of TV shows and appeared in several movies) but also a strange sort of social activism which helped push the boundaries of free speech in the '70s.

His dark social satire, which often criticized the flaws in modern-day America, was sometimes obscene, but always insightful. Carlin was always controversial, back from the day when that wasn't a trend. He was arrested several times, mostly in the 60s and 70s due to his anti-government views and actions. George Carlin was also the first person to host Saturday Night Live.

His best-known routine, "Seven Words You Can Never Say on Television", led to his arrest on July 21, 1972 at Milwaukee's Summerfest. He was charged with violating obscenity laws, but a judge ruled that the language was indecent but cited free speech in letting him go. Carlin's troubles continued next year after he broadcast a similar routine on WBAI, a Pacifica Foundation FM radio station in New York City.

The case eventually went all the way up to the Supreme Court, which ruled 5 to 4 that the routine was "indecent but not obscene", and the FCC had authority to prohibit such broadcasts because children are likely to be among the audience.

George Carlin snatched four Grammy Awards and three American Comedy Awards, the last of which was for Lifetime Achievement Award in Comedy in 2001. Just four days before his death, it was announced by the Kennedy Center for the Performing Arts in Washington, DC that Carlin was selected as the 2008 honoree of the Mark Twain Prize for American Humor to be awarded in November.

Carlin's wife, Brenda Hosbrook, died after 36 years of marriage in 1997. They had a daughter, Kelly, born in 1963.