Letterman will host his last The Late Show on Wednesday (20May15) and, in an article for the Huffington Post, the former 30 Rock star reveals what he will miss most about the retiring 68 year old.

He writes, "As a kid growing up in the 60's and 70's, I stayed up late and watched a lot of the Tonight Show with Johnny Carson... If you wanted to laugh and enjoy yourself, you watched Carson, a show that made you feel you were at a party thrown by some funny, hip people. After Carson left, it was difficult to imagine that someone fresh would appear on late night TV until David Letterman came along."

He continues, "Where other hosts weren't all that interested in what you had to say, Letterman's segment producers drove home the point that Dave wanted you to not only participate, but to be entertaining - if not genuinely funny. Doing the show was never a chore. It was fun.

"Letterman himself, of course, can be intimidating. Going on his show and matching wits with him is something few can pull off. But over the past several years, audiences have had an experience with Letterman that they've had with very few entertainers. We've watched him grow and change..."

He adds, "(I will miss) the cynical, bold, silly, unselfconscious, totally self-conscious nut from Indiana who became TV's greatest host."