John Mehegan (June 6, 1916 – April 3, 1984) was an American jazz pianist, lecturer and critic.
Mehegan was born in Wethersfield, Connecticut, and began playing the piano at the age of five. He taught himself to play by matching his fingers to the notes played on a neighborhood player piano. His mother gave him violin lessons, but he preferred piano. In 1941 he arrived in Manhattan where he lived with his first wife, Doris and their two children Carey and Gretchen. He had the opportunity to play at the legendary Marie's Crisis bohemian club in Greenwich Village. In 1946, he was appointed head of the jazz department at the Metropolitan Music School in New York. He wrote the incidental music for A Streetcar Named Desire which he performed on Broadway for two years. In the early 1950s he played a honky-tonk saloon piano player on The Gabby Hayes Show television series. Mehegan also had a run-in with the House Un-American Activities Committee where he was an uncooperative witness and this had a negative effect on his career, limiting some career possibilities for about a decade. Also during the 1950s Mehegan was a regular attendee at the Tanglewood Music Festival in Massachusetts. He later held posts at the Juilliard School of Music and Yale University. He was the jazz critic for the New York Herald Tribune.
Mehegan played solo piano for many years at the Composer's Lounge, Ambassador Grill and Lounge and the Drake Room in New York City, as well as the River Cafe in Brooklyn, NY. He also played at numerous clubs in Southwest Connecticut, where he lived with his third wife and three children.
He authored numerous books on jazz, including the Jazz Improvisation series, which sets out the basic principles of jazz. These are published in seventeen languages and sold around the world.
The American composer Leonard Bernstein dedicated a piano composition to Mehegan in his Four Anniversaries collection published in 1948. Marked agitato: scherzando, the piece, For Johnny Mehegan, commemorates Mehegan's birthday, June 6, 1920, which is actually not the year he was born.