William Clarke (c. April 1609 – 1671) was an apothecary who provided lodgings for a young Isaac Newton whilst he attended the King's School in Grantham.
Clarke eventually retired to Loughborough in Leicestershire, leaving his business to his son, William.
The town of Grantham was captured by Royalists on 23 March 1643[2] and on 11 April he was indicted for high treason.
In 1654, William provided boarding to Isaac Newton as he would be attending the King's School with Edward and Arthur Storer.
According to the Clarke's grandson, Ralph Clarke, also an apothecary in Grantham, Newton left signs of his presence in the garret where he slept in the apothecary's house on Grantham's High Street: he carved his name into the boards, and drew charcoal drawings of birds and beasts, men and ships, and abstract shapes on the walls.