William Mead (1628–1713) was a London merchant, and a prominent early Quaker, connected by marriage to George Fox.
Mead became a wealthy linen draper of Fenchurch Street in the City of London, and member of the Company of Merchant Taylors. He was captain of a train-band, before joining the Quakers in 1670. On 14 August of that year he was present at a crowded meeting in Gracechurch Street, at which William Penn was the preacher; both were arrested and committed to Newgate Gaol.
The trial of Penn and Mead, at which they defended the right of free worship, began at the Old Bailey on 1 September 1670. They were accused of disturbing the peace by unlawfully assembling together by agreement, and pleaded not guilty. The jury pronounced on 5 September that Penn was not guilty of breaking the law, and that Mead was not guilty at all; but jury and prisoners were committed to Newgate. Penn's father, Sir William Penn, was stated by Gerard Croese to have paid fines to secure their release. A detailed account of the trial, under the title The People's Ancient and Just Liberties asserted, was published (London, 1670) by Penn and Mead, and it is also related at length by Joseph Besse in his Collection of the Sufferings of the People called Quakers.
The handling of the trial gave rise to Bushel's Case. Thomas Vere, the jury foreman, paid a fine and was released. Edward Bushel(l), one of a group of four jurors who disputed their treatment, successfully applied to the Court of Common Pleas for a writ of habeas corpus, and they were released, following a ruling by Sir John Vaughan.