Sir Thomas Myddelton (1550 – 12 August 1631^[1]) was a Welsh merchant who was Lord Mayor of London before becoming a Member of Parliament for London.

He was the fourth son of Richard Myddelton, Governor of Denbigh Castle, and Jane Dryhurst.^[2] Among his siblings were William Myddelton, a poet and seaman,^[3] Sir Hugh Myddelton, 1st Baronet, a merchant and clothmaker,^[4] and Robert Myddelton, MP for Weymouth and Melcombe Regis and the City of London.^[5]

As a youth, he was apprenticed to a grocer in London, and made his fortune in trade. He divided his time between London and Wales, and purchased Chirk Castle in 1595 for £5,000.

He was a member of the Grocers' Company, a Member of Parliament for the City of London and a founder member of the East India Company, Sheriff of London in 1604 and Lord Mayor of London in 1613. His brother, Sir Hugh Myddleton, was instrumental in the creation of the New River which supplied London with fresh water from 1613.^[6] He was knighted in July 1603.^[2]

Along with Rowland Heylyn, Myddelton financed the publication of a Welsh language Bible suitable for everyday use.^[7]

Myddelton was married four times. His first marriage was on 18 February 1584 to Hester Saltonstall (1555–1587), a daughter of Sir Richard Saltonstall, also a Lord Mayor of London who served as MP for London and as Sheriff of the City of London. Her sister, Eleanor Saltonstall, married Myddelton's brother Robert, in 1612. Before her death in July 1587, they were the parents of two sons:^[2]

• Thomas Myddelton of Chirk Castle (c. 1586–1666), who married twice: first to Margaret Savile, daughter of George Savile of Wakefield in Yorkshire, and secondly to Mary Napier, a daughter of Sir Robert Napier, 1st Baronet, of Luton Hoo, Bedfordshire, with whom he had seven sons and six daughters.
• Richard Myddelton (1586–c. 1607),^[8] who married Katherine Herne, widow of Henry Herne, in 1604.^[9][10]

After her death, he married Elizabeth Olmstead, widow of John Olmstead of Ingatestone, Essex, by 25 March 1588. They were the parents of two sons and two daughters:^[2]

• Henry Myddelton, who died young.^[8]
• Timothy Myddelton (c. 1590–1655),^[8] who inherited his estates in Essex; he married Martha Johnson, a daughter of Robert Johnson, alderman of London.^[11]
• Hester Myddelton (d. 1614), who married Sir Henry Salusbury, 1st Baronet, the grandson of Catherine of Berain and a cousin of Elizabeth I.^[12]
• Mary Myddelton (d. c. 1681), who married Sir John Maynard, the second son of Sir Henry Maynard, of Estaines Parva.^[8]

His third marriage was in 1604 to Elizabeth (née Brooke) Thorpe Hobart (d. 1619/20), a daughter of Richard Brooke, a goldsmith of London. She was twice a widow, having been married to Richard Thorpe (d. 1591), a vintner of London and Miles Hobart (d. 1604), a clothworker of London. By his third marriage he gained a stepson, Miles Hobart.^[2] She died in 1619.

His fourth marriage was to Anna (née Vanaker) Wittewronge, a daughter of Garrard Vanaker of Antwerp, widow of Jacob Wittewronge, a brewer of London.^[2] By his fourth marriage, he gained another stepson, John Wittewrong,

Myddelton died on 12 August 1631. His younger son, Timothy, inherited his estates in Essex.^[11]