American comedian and writer best known as the longtime host of The Tonight Show (Tonight Show, The) (1992– ).

Leno was raised in Andover, Mass. While attending Emerson College in Boston, where he graduated (1972) with a degree in speech therapy, he worked as a stand-up comic in nightclubs. After moving to Los Angeles, he served as the opening act for such entertainers as Johnny Mathis and Tom Jones. Leno debuted on NBC (National Broadcasting Co., Inc.)'s The Tonight Show in 1977 and became Johnny Carson (Carson, Johnny)'s permanent guest host 10 years later. In 1992 NBC chose Leno over David Letterman (Letterman, David) to replace the retiring Carson. The selection spawned a rivalry between The Tonight Show and CBS's The Late Show with David Letterman (1993– ), which competed in the same timeslot. Despite the controversy, Leno soon earned a reputation for his cordial, easygoing manner, strong work ethic, and knack for connecting with his audience. He gave the show a trendy, casual image, with edgier musical acts and new comedy segments, including “Jaywalking,” in which people on the street were asked basic questions that they often answered incorrectly, and “Headlines,” which showcased funny newspaper headlines from around the country. Under Leno's leadership, the program garnered four Emmy Awards (1995–97; 1999), and Leno was awarded numerous accolades, including a star on Hollywood's Walk of Fame in 2000. By 2008 the show had topped the ratings charts with more than five million viewers, nearly one and a half times that of its nearest rival, The Late Show. With his contract scheduled to expire, Leno planned to leave The Tonight Show in May 2009, but in December 2008 he announced plans to stay with the network in order to host a prime-time, hour-long show that would air Monday through Friday.

Early in his career, Leno worked as a writer (1974) for the television situation comedy Good Times and occasionally took acting jobs on sitcoms, such as Laverne & Shirley, Friends, and Seinfeld, and in films, including Wayne's World 2 (1993), The Flintstones (1994), and Wag the Dog (1997). Leno also provided the voice for characters based on himself in animated TV shows, such as The Simpsons, South Park, and Family Guy, and movies, notably Cars (2006).

In addition to his comic fame, Leno was recognized as an automotive authority. He wrote a column, “Jay Leno's Garage,” for Popular Mechanics magazine and contributed to several books, including Velocity: Supercar Revolution (2006), Legendary Motorcycles (2007), and The Hemi in the Barn: More Great Stories of Automotive Archaeology (2007).

Leno's anecdotal memoir, Leading with My Chin, appeared in 1996. His books written for children, If Roast Beef Could Fly and How to Be the Funniest Kid in the Whole Wide World (or Just in Your Class), followed in 2004 and 2005, respectively.