John R. Adler (born 1954) is an American neurosurgeon. He is the inventor of the CyberKnife radiosurgical instrument. In 2007 he was named the Dorothy and Thye King Chan Professor of Neurosurgery at Stanford University School of Medicine. He was also the school's vice chair for innovation and technology. He is currently an emeritus professor of neurosurgery. In April 2010, Adler was appointed vice president and chief of New Clinical Applications at Varian Medical Systems.