Arnold William Klein (February 27, 1945 – October 22, 2015) was an American dermatologist. In 1983 Michael Jackson became one of Klein's patients. He was a member of the Advisory Board of the AIDS Services Foundation Orange County. He has published over 150 scientific papers.
Klein was born in Michigan. His father was a Jewish Orthodox rabbi. In 1971 he got his doctorate in medicine from the University of Pennsylvania School of Medicine.
Klein was gay. In 2015, Klein died at the age of 70. No cause of death was given.