Sir John Wynn, 1st Baronet (1553 – 1 March 1627), was a Welsh baronet, Member of Parliament and antiquary.
He was the son of Morys Wynn ap John, who he succeeded in 1580, inheriting Gwydir Castle in Carnarvonshire. John was educated at All Souls College, Oxford (1570, awarded BA 1578) and studied law at Furnival's Inn (1572) and the Inner Temple (1576). He claimed to be directly descended from the princes of Gwynedd through Rhodri ab Owain son of Owain Gwynedd. The male line from his family died out in 1779 (see 'Legacy' section below) and the senior male line passed to the Anwyl of Tywyn family. However, this claim is disputed in a publication of 1884 entitled Gweithiau Gethin published by W. J. Roberts in Llanrwst..
He was Member of Parliament for this county in 1586 and served as Sheriff of Caernarvonshire for 1587–88 and 1602–03 and Sheriff of Merionethshire for 1588–89 and 1600–01. He was appointed Deputy Lieutenant of Caernarvonshire in 1587, a member of the Council of the Marches of Wales c.1603 and Custos Rotulorum of Caernarvonshire in 1618 (to 1627).
In 1606 he was made a knight and in 1611 became the first of the Wynn baronets. He was interested in several mining ventures and also found time for antiquarian studies.
He married Sydney, the daughter of William Gerard, and had 10 sons and 2 daughters. His successor was his second and eldest surviving son Richard.