German-born master organ builder in Restoration England.

Smith was an apprentice of the German organ builder Christian Förmer but adapted easily to the English style of building after his emigration there in 1660. Some years after building an instrument for the Chapel Royal at London, Smith was named king's organ maker (1681). Thereafter he built many important instruments, some of which survive. Much of his pipework was incorporated into later instruments. He was organist at St. Margaret's, Westminster, from 1675.

Smith's organs are considered to have been generally superior in tone to those built by his rival Renatus Harris (Harris, Renatus) (q.v.), as the tone of Smith's wooden pipes was particularly attractive. Organs built by Harris are, however, considered to have been mechanically superior to Smith's.

Smith was a friend of the composers John Blow and Henry Purcell, whom he consulted in musical matters, and, despite his reputedly poor use of the English language, he was a member of a club founded by the scholar Richard Bentley that included Matthew Locke, Sir Isaac Newton, Sir Christopher Wren, and other outstanding figures of the time.