Alexander Mitchell, (13 April 1780 – 25 June 1868) was an Irish engineer who from 1802 was blind. He is known as the inventor of the screw-pile lighthouse. Born in Dublin, his family moved to Belfast while he was a child, and he received his formal education at Belfast Academy – where he excelled in mathematics. In 1848 he was elected member of the Institution of Civil Engineers and received the Telford Medal the following year for a paper on his invention. He became friendly with astronomer John Thomas Romney Robinson, and mathematician George Boole.