“The role of a comedian is to make the audience laugh, at a minimum of once every fifteen seconds.”

"Creator — A comedian whose audience is afraid to laugh." — H.L. Mencken, A Book of Burlesques‎ (1920), p. 203. and A Mencken Chrestomathy (1949), Ch. 30
Misattributed

At Piers Morgan Tonight, 2011

Entertainment Weekly interview http://www.jerriblank.com/colbert_ew.html, August 13, 2004, on his character break during the infamous Prince Charles sketch on The Daily Show.
Context: Such a proud moment of professionalism. You work for years crafting cogent satirical essays and the thing that everybody remembers is me making love to a Chiquita and bursting into laughter. What you can't see off camera is Jon started laughing first. And then I'm weak. As much as I want to make the audience laugh, I really want to make Jon laugh.

Source: Watchmen

Second obituary on BBC news website http://news.bbc.co.uk/1/hi/entertainment/1958051.stm

When asked what he perceives his role to be, given that many young people claim to get their news from The Daily Show and The Colbert Report, on newsman. "Harvard University: A Conversation with Stephen Colbert" http://ksgaccman.harvard.edu/iop/events_forum_video.asp?ID=3051 (1 December 2006).
Context: I don't perceive my role as a newsman at all. I'm a comedian from stem to stern. You can cut me open and count the rings of jokes. If people learn something about the news by watching the show, that is incidental to my goal.

Source: "Test of a Comedian", The American Mercury (September 1929)

Comedians in Cars Getting Coffee (2012 — Present), Season 3 (2014)