Jessica Jennifer Williams (March 17, 1948 - March 10, 2022) was an American jazz pianist and composer.

Williams was born in Baltimore, Maryland, on March 17, 1948. She started playing the piano at age four, began music lessons with a private teacher at five, and at age seven was enrolled into the Peabody Preparatory. She studied classical music and ear training with Richard Aitken and George Bellows at the Peabody Conservatory of Music.

At age twelve, Williams was listening to Dave Brubeck, Miles Davis, and Charles Mingus. She began performing jazz in her teens, playing with Richie Cole, Buck Hill, and Mickey Fields. In a radio interview with Marian McPartland on NPR's Piano Jazz from 1992, she stated that her main influences were not pianists, but reed and brass players such as John Coltrane and Miles Davis.

According to her own words, "I was just a problem when it came to authority" and this carried over to her professional life as she developed her own style of playing, as heard on her version of "Getting Sentimental Over You", where she would strum the strings inside the piano itself, a clear way for her to break convention.

In June 1976, Williams began performing regularly with the "Philly Joe" Jones band in New Jersey, and with Lex Humphries in Philadelphia and New York City, before moving to the West Coast in October 1976.

In 1977, Williams moved to San Francisco, where she played in house bands at the Keystone Korner. She worked with Eddie Harris, Tony Williams, Stan Getz, Bobby Hutcherson, and Charlie Haden, eventually leading her own jazz trio, and recording regularly for several decades.

In 1997, Williams established her own record label, Red and Blue Recordings. She also started her publishing company, JJW Music/ASCAP, and an internet mail order business.

Williams appeared at the 2004 and 2006 "Mary Lou Williams Women in Jazz Festival" at the John F. Kennedy Center for the Performing Arts in Washington, D.C. She also appeared in festivals and venues worldwide, including The Purcell Room in London, The Bern Jazz Festival, The Monterey Jazz Festival, The New Morning in Paris, Spivey Hall in Georgia, and hundreds of other venues. She was a guest on NPR's Fresh Air with Terry Gross, and Marian McPartland's Piano Jazz on NPR, as well as an appearance at the Brecon Jazz Festival in Wales, which was filmed by the BBC, she was however "disappointed when only a fifteen minute segment was shown and her attempts to get the material for her own use were unsuccessful".