Sir William Coventry PC (c. 1628 – 23 June 1686) was an English statesman.
William was the son of the lord keeper Thomas Coventry, 1st Baron Coventry, by his second wife Elizabeth Aldersley. Coventry matriculated at Queens College, Oxford, at the age of fourteen. Owing to the outbreak of the English Civil War he was forced to abandon his studies, but according to Sir John Bramston, the younger he had a good tutor, and through travelling he learned to speak the French language fluently. He was young at the time of the war, yet Clarendon wrote that he joined the army and had the command of a foot company and shortly afterwards went to France. Here he remained till all hopes of obtaining foreign assistance and of raising a new army had to be laid aside, when he returned to England and kept aloof from the various royalist intrigues. When the prospect of a restoration appeared in 1660, Coventry hurried to Breda, was appointed secretary to James, Duke of York (who was Lord High Admiral of England) and headed the royal procession when Charles II entered London in triumph.
Coventry was returned to the Restoration Parliament of 1661 for Great Yarmouth, became commissioner for the navy in May 1662 and in 1663 was made D.C.L. at Oxford. His great talents were very soon recognised in parliament, and his influence as an official was considerable. His appointment was rather that of secretary to the admiralty than of personal assistant to the duke of York, and was one of large gains. Anthony Wood states that he collected a fortune of £60,000. Accusations of corruption in his naval administration, and especially during the Dutch war, were brought against him, but there is no real evidence for this. Samuel Pepys, in his diary, testifies to the excellence of Coventry's administration and to his zeal for reform and economy; his consistent praise for Coventry is in notable contrast to his strictures on his other colleagues, who are generally referred to as "knaves" or "old fools". Coventry's ability and energy did little to avert the naval collapse, owing chiefly to financial mismanagement and ill-advised appointments.