American dental surgeon who in 1846 gave the first successful public demonstration of ether anesthesia (anesthetic) during surgery. He is credited with gaining the medical world's acceptance of surgical anesthesia.

Morton began dental practice in Boston in 1844. In January 1845 he was present at Massachusetts General Hospital, Boston, when Horace Wells, his former dental partner, attempted unsuccessfully to demonstrate the anodyne properties of nitrous oxide gas. Determined to find a more reliable pain-killing chemical, Morton consulted his former teacher, Boston chemist Charles Jackson (Jackson, Charles Thomas), with whom he had previously done work on pain relief. The two discussed the use of ether, and Morton first used it in extraction of a tooth on Sept. 30, 1846. On October 16 he successfully demonstrated its use, administering ether to a patient undergoing a tumour operation in the same theatre where Wells had failed nearly two years earlier.

Unfortunately, Morton attempted to obtain exclusive rights to the use of ether anesthesia. He spent the remainder of his life engaged in a costly contention with Jackson, who claimed priority in the discovery, despite official recognition accorded to Wells and the rural Georgia physician Crawford Long.