Jason Ignatius Marsalis (born March 4, 1977) is an American jazz drummer, vibraphone player, composer, producer, band leader, and member of the Marsalis family of musicians. He is the youngest son of Dolores Ferdinand Marsalis and the late Ellis Marsalis, Jr.

Marsalis was born in New Orleans, Louisiana, the son of Dolores (née Ferdinand) and Ellis Louis Marsalis, Jr., a pianist and music professor. His brothers are Branford Marsalis, Wynton Marsalis, Ellis Marsalis III (1964), Delfeayo Marsalis, and Mboya Kenyatta (1971). Branford, Wynton, and Delfeayo are also jazz musicians.

At age 6, Marsalis took lessons from legendary New Orleans drummer James Black. As a teenager, he made his recording debut on Delfeayo Marsalis's 1992 release, Pontius Pilate’s Decision.

Marsalis graduated from the New Orleans Center for Creative Arts (NOCCA) and studied percussion at Loyola University New Orleans. He worked as a sideman in mainstream jazz, funk, and jazz fusion groups (Neslort and Snarky Puppy); a Brazilian percussion ensemble (Casa Samba); and played Celtic music with Beth Patterson. He introduced percussionist Bill Summers to trumpeter Irvin Mayfield, and they founded Los Hombres Calientes. Marsalis has also played with John Ellis, Dr. Michael White, and the Marsalis family. Marsalis regularly performs at the New Orleans Jazz & Heritage Festival as leader and sideman.

Marsalis has had a long professional career and collaboration with pianist Marcus Roberts. In 1994 at the age of 17 he toured as a member of the Marcus Roberts Trio performing selections from Roberts' Gershwin for Lovers. In 2022 he continues performing with Marcus Roberts as a member of the trio and Robert's Modern Jazz Generation. In a program of Duke Ellington songs at Carnegie Hall with Marcus Roberts, bassist Rodney Jordan, vocalist Catherine Russell, and the American Symphony Orchestra, critic Seth Colter Walls writes "The drumming by Marsalis was likewise individual in character, particularly during "Three Black Kings." (At one point, he made a simple-sounding pattern progressively complex in its syncopations, until he stirred the crowd to applause.)"

At the age of 21, Marsalis released his first record as leader, The Year of the Drummer. "On this impressive debut, his quintet puts together a highly coordinated spin on blues motifs and Caribbean figures. The music is vivacious as it makes its move; all sorts of fresh ideas concerning tempo fill the air."

Los Angeles Times’ writer Don Heckman reviewed Marsalis's second record, the 2000 release, Music in Motion, and described it as "impressive," "the opportunity to display his technique in everything from brushwork and hard-driving jazz to offbeat meters and Brazilian rhythms...with ease," and "purposeful, intelligent drumming." The record's cover photograph is of Jason standing on the tracks of the New Orleans Public Belt Railroad along Leake Avenue in New Orleans.

In 2009, Marsalis released his first album as a leader on vibraphone, entitled Music Update. The album received 4.5 out of 5 stars in DownBeat magazine. Writing in The New York Times, critic Ben Ratliff said that Marsalis was "an excellent musician trying out something risky without embarrassment."