William Lilly, an English astrologer, born at Diseworth, Leicestershire, May 1, 1602, died at Walton-upon-Thames, June 9, 1681. In 1620 he went to London and secured a position as footboy to a merchant, who afterward employed him as an accountant. His master dying in 1627, Lilly married the widow, with whom he received £1,000. He began the study of astrology in 1632, and soon practised with eminent success, and instructed many persons in the art. In 1644 he produced the first number of his almanac, Merlinus Anglieus Junior, which contained remarkable prognostications, was purchased with avidity, and was continued for many years. He was consulted both by the royalists and parliamentarians in the civil war. In 1651 he published "Monarchy or no Monarchy," containing several hieroglyphical figures, two of which were subsequently declared to have had reference to the plague and the great fire in London, and he was consequently summoned in 1666 before a committee of the house of commons. He afterward practised medicine in connection with his astrological science, till he was enfeebled by age.

He published an autobiography (London, 1715), an "Introduction to Astrology" (new edition, with emendations and additions by Zadkiel, London, 1852), and other works.