Mark Sandman (September 24, 1952 – July 3, 1999) was an American singer, songwriter, musical instrument inventor, multi-instrumentalist and comic writer. Sandman possessed a distinctive, deep bass-baritone voice and a mysterious demeanour. He was an indie rock icon and longtime fixture in the Boston/Cambridge music scene, best known as the lead singer and slide bass player of the band Morphine. Sandman was also a member of the blues-rock band Treat Her Right and founder of Hi-n-Dry, a recording studio and independent record label.

He was highly regarded by many other bass players for his unique "slow and murky" style, with Les Claypool, Mike Watt, and Josh Homme all citing Sandman as an influence

On July 3, 1999, he suffered a heart attack during a concert at the Giardini del Principe in Palestrina, Lazio, Italy

His death has been attributed to heavy stress and the temperature of over 99 °F (37 °C) on the night of his death. Morphine disbanded following his death, although the surviving members briefly toured with other musicians as Orchestra Morphine, a tribute to Sandman and in support of the posthumous release, The Night.