Sir William Meyrick, or Mericke, (died 3 February 1667–8) was an English civil lawyer and judge.
Meyrick was the son of Maurice Meyrick of Bodeon, Anglesey, by Jane, daughter of Lewis Evans, was admitted scholar of Winchester College in 1608, scholar of New College, Oxford, on 16 July 1614, and fellow on 16 July 1616; he graduated B.C.L.
He resigned his fellowship in 1626, and was admitted a member of the College of Advocates on 2 February 1627–8, and practised before the court of high commission.
On 28 September 1641 he succeeded Sir Henry Martin as judge of the prerogative court of Canterbury.
In 1643 he joined the king at Oxford, whence on 8 May he issued a notice revoking the powers of his deputies at Canterbury.