Hugh Mackay (c. 1640 – 24 July 1692) was a Scottish military officer who settled in the Netherlands, and spent most of his career in the service of William of Orange (later William III of England). In 1660, Mackay was commissioned into Dumbarton's Regiment, spending the next few years in England and France, then volunteered to fight for the Republic of Venice in the Fifth Ottoman-Venetian War. He rejoined Dumbarton's in 1672 on the outbreak of the Third Anglo-Dutch War, before transferring to the Scots Brigade in 1673. A long established mercenary unit of the Dutch army, Mackay served with the Brigade for the rest of his career.