How comedians pushing the boundaries made a difference. Watch CNN's Original Series, "History of Comedy," Sundays at 10pm ET/PT.
Bruce broke down doors for future comics by angering authorities with his unfiltered routines about drugs, race and religion.
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His "7 words you can't say on TV" routine went to the Supreme Court. It ruled Carlin's joke was "indecent but not obscene," upholding free speech.
Lear produced sitcoms like "All in the Family" that made TV more socially relevant by addressing thorny issues like racism, homosexuality, menopause and misogyny.
Pryor's fearless discussion of race inspired giants like Eddie Murphy, Damon Wayans and Chris Rock.
After Ellen DeGeneres came out as gay, she played the first lead character on US TV to come out, leading to major LGBT characters in shows like "Will & Grace" and "Glee."
Show creators Trey Parker and Matt Stone skewered religion, ethnic groups, celebrities and other targets, largely obliterating TV's last remaining taboos.