Tobias Rustat (1606?–1694) was a servant to Charles II and benefactor of the University of Cambridge. He is best remembered for creating the first fund for the purchase of books at the Cambridge University Library. The Rustat Conferences based at Jesus College, Cambridge are named after him.
After an apprenticeship to a barber-surgeon in London, Rustat entered the service of William Feilding, 1st Earl of Denbigh, before becoming servant to George Villiers, 2nd Duke of Buckingham. An ardent Royalist, Rustat joined Buckingham in an uprising in Kent, where he saved the Duke's life. He was also present following the Battle of Worcester and aided Prince Charles's escape. In 1648 he escaped to the continent with Buckingham. During this time Rustat acted as a courier between England and the exiled king's court.
In 1650 Rustat was made Yeoman of the Robes to Charles II, remaining in the position until the king's death in 1685.
Rustat is buried in the chapel of Jesus College, Cambridge.
In his later life Rustat became an important benefactor to a number of colleges of the University of Cambridge, in particular to Jesus College where his father had been a student. In January 1667 he created the first fund for the purchase of books at the Cambridge University Library with a donation of £1000. The books purchased from the fund were to be stamped with Rustat's crest.
Rustat also created a scholarship at Jesus College for the sons of deceased Anglican clergyman. Samuel Taylor Coleridge later attended Jesus as a Rustat Scholar.
He was awarded a Master of Arts degree per literas regias in 1674.