I was four years old when Late Night With David Letterman premiered on 1 February 1982. There was no way I could have watched it, nor, I suspect, would I have had much interest in doing so. Witching-hour talk shows weren’t on the radar of a boy into Saturday morning cartoons and Star Wars. Yet I can’t recall a time when I wasn’t at least aware of the show’s gap-toothed host, a contemporary of mine in the sense that he cultivated his celebrity while I came of age. Other US TV hosts like comedians Johnny Carson and Jack Paar were already institutions. But Letterman was the new kid on the block, invigorating the format with his own oddball sense of humour, and lending it an abrasive edge that pushed back against Carson and Paar’s audience-ingratiating gentility. A medium that had been relentlessly ‘nice’ would never be the same. Even across the Atlantic, TV hosts were taking notice: in 1987 Jonathan Ross would pattern The Last Resort, his UK TV programme, on Late Night. But being the rebellious upstart would only last for so long. Letterman would quickly become an icon himself – for better and for worse.

Source: BBC – Culture – David Letterman: The man who changed TV forever