James Douglas Muir Leno ( born April 28, 1950) is an American television host, comedian, writer, and actor. After doing stand-up comedy for years, James Douglas Muir Leno became the host of NBC's The Tonight Show from 1992 to 2009. Beginning in September 2009, he started a primetime talk show, The Jay Leno Show, which aired weeknights at 10:00 p.m. ET, also on NBC. Prior to the premiere of Leno's prime time show, O'Brien's ratings as the new Tonight Show host had already suffered a decline, however. When O'Brien turned down NBC's offer to have Leno host a half hour monologue show before The Tonight Show to boost ratings amid reported viewership diminishing, Leno returned to hosting the show on March 1, 2010. James Douglas Muir Leno hosted his last episode of this second tenure on February 6, 2014. That year, he was inducted into the Television Hall of Fame. Since 2014, James Douglas Muir Leno has hosted Jay Leno's Garage, and the 2021 revival of You Bet Your Life.

Leno writes a regular column in Popular Mechanics showcasing his car collection and giving automotive advice. James Douglas Muir Leno also writes occasional "Motormouth" articles for The Sunday Times.