Mark Helias (born October 1, 1950) is an American jazz double bass player and composer born in New Brunswick, New Jersey.
He did not begin playing the double bass until the age of 20, graduating from Yale University's School of Music with a Masters degree in 1976. He has also studied at Rutgers University. He teaches at Sarah Lawrence College, The New School, and SIM (School for Improvised Music).
Helias has performed with a wide variety of musicians, first and foremost with trombonist Ray Anderson, with whom he led the ironic 1980s avant-funk band Slickaphonics, and a trio with Gerry Hemingway on drums, formed in the late 1970s, later named BassDrumBone, and continuing to play together. Besides Helias performed with the previous members of Ornette Colemans original band, Don Cherry, Dewey Redman, and Ed Blackwell, just as with musicians affiliated with the AACM, such as Anthony Braxton, Anthony Davis, Muhal Richard Abrams, and Julius Hemphill. Furthermore he played with Cecil Taylor, Marilyn Crispell, Simon Nabatov, and reed players Oliver Lake, Carlos Ward, Arthur Blythe, Don Byron, and Marty Ehrlich, whereas less usual were performances with Abbey Lincoln, Mose Allison, and J.B. Horns.
Since 1984 Mark Helias has released six recordings under his own name and further six albums leading the archetypal improvising trio Open Loose since 1996. The group comprises Helias on bass, first Ellery Eskelin, then Tony Malaby on tenor saxophone and Tom Rainey on drums.