John Mostyn was a Welsh politician who sat in the House of Commons

House of Commons of England

The House of Commons of England was the lower house of the Parliament of England from its development in the 14th century to the union of England and Scotland in 1707, when it was replaced by the House of Commons of Great Britain...

  at various times between 1625 and 1640.

Mostyn was the son of Sir Roger Mostyn of Mostyn. In 1624 he was elected Member of Parliament

Member of Parliament

A Member of Parliament is a representative of the voters to a :parliament. In many countries with bicameral parliaments, the term applies specifically to members of the lower house, as upper houses often have a different title, such as senate, and thus also have different titles for its members,...

 for Anglesey. He was entered at Middle Temple

Middle Temple

The Honourable Society of the Middle Temple, commonly known as Middle Temple, is one of the four Inns of Court exclusively entitled to call their members to the English Bar as barristers; the others being the Inner Temple, Gray's Inn and Lincoln's Inn...

 in November 1637.

In April 1640, Mostyn was elected MP for Flintshire

Flintshire (UK Parliament constituency)

Flintshire was a parliamentary constituency in North-East Wales which returned one Member of Parliament to the House of Commons of the Parliament of the United Kingdom from 1542 until it was abolished for the 1950 general election.- Boundaries :...

 in the Short Parliament

Short Parliament

The Short Parliament was a Parliament of England that sat from 13 April to 5 May 1640 during the reign of King Charles I of England, so called because it lasted only three weeks....

. He was re-elected MP for Flintshire for the Long Parliament

Long Parliament

The Long Parliament was made on 3 November 1640, following the Bishops' Wars. It received its name from the fact that through an Act of Parliament, it could only be dissolved with the agreement of the members, and those members did not agree to its dissolution until after the English Civil War and...

in November 1640. He was disabled from sitting in parliament for supporting the King on 5 February 1644. He was assessed at £1,000 by the Committee for the Advance of Money on 28 July 1644.

Mostyn died unmarried at his seat at Maesmynau in 1644.