Celebrities, comedians and presidents have posted online farewells and tributes to legendary comedian David Letterman, whose final Late Show was watched by nearly 14 million people when it aired on Wednesday.

Letterman, 68, retired this week after taping more than 6,000 episodes of his late night talk show in a career that spanned 33 years.

The final episode featured past presidents and a bevy of celebrities, just as the show had since it started in 1993.

Some of the social media tributes included:

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