Blaster Al Ackerman (born William Hogg Greathouse Jr.; November 27, 1939 – March 17, 2013) was an American mail artist and writer.

Al Ackerman's writing, including poetry and short stories, has dealt playfully, if obsessively, with themes of madness and weird phenomena.

His visual work is also in the tradition of black humor, often including a trademark character, the hebephrenic, with a wide upper lip and two protruding teeth.

His voluminous mail art output was anthologized in The Blaster Omnibus in 1994, and given a one-man show at the Chela Gallery in Baltimore, Maryland in the early 21st century.

His influence in the 1980s was strongly felt by neoism founder Istvan Kantor, performance artist Andre Stitt, photographer Richard Kern (who published Ackerman's writing in his magazine Dumb Fucker) and musician Genesis P-Orridge who used one of Ackerman's letters as the text of Throbbing Gristle's song "Hamburger Lady.