Mason, William Monck (1775–1859), historian, was born 7 September 1775 in Dublin, the eldest son of Henry Monck Mason, a colonel of engineers, and his second wife, Jane Mason (née Mosse), a daughter of the surgeon and philanthropist Bartholomew Mosse (qv). His uncle was John Monck Mason (qv), the politician and literary commentator, and his brother was Henry Joseph Monck Mason (qv), the writer, librarian, and evangelical reformer. In 1796 William succeeded his father as land waiter for exports in the Dublin revenue department, a sinecure that allowed him to dedicate his life to historical scholarship.
He began work on a vastly ambitious topographical study of Ireland, that was never completed, but which created great interest. The first part, The history and antiquities of the collegiate and cathedral church of St Patrick, was published in 1819 and included a lengthy biography of Jonathan Swift (qv). The book won much praise, but Mason did not complete his intended sequel, a history of Christ Church. In 1823 he published a prospectus for a new history of Dublin, and this was followed in 1825 by a pamphlet of suggestions for the survey and valuation of Ireland. Both were critical of existing works, but neither led to anything further.
After his sinecure was abolished in 1826 Mason was awarded an annual pension by the government and he left Ireland to travel on the continent. He sold his library and various collections of fine art in London between 1834 and 1837, and thereafter concentrated on the study of philology. In 1848 he moved to England, where he resided for the remainder of his life. Within a few years he had amassed another enormous library, which he sold at auction in 1852. His literary collections and notes on Irish history were also sold at auction, in 1858. He died 6 March 1859 at Surbiton, Surrey. He married, but there are no details of his wife.