In early Greek mythology Cheiron, the son of Cronus and Philyra was a Thessalian god of healing and the first teacher of Occupational Medicine.
He was wise and had an extensive knowledge of the healing arts and was the tutor of amongst others, Asclepius, Theseus and Achilles.
In later mythology he survived as one of the centaurs.
When he was accidentally hit by a poisonous arrow shot by Heracles, Cheiron relinquished his immortality (in favor of Prometheus) in order to escape the pain by dying.
After his death he became the constellation of Sagittarius.