Sir Roger Mostyn, 5th Baronet

Sir Roger Mostyn, 5th Baronet (13 November 1734 – 26 July 1796) was a Welsh landowner and politician who sat in the House of Commons for 38 years from 1758 to 1796.

Mostyn was returned unopposed as Member of Parliament for Flintshire at a by-election on 26 April 1758 replacing his late father.

His family had the dominant electoral interest in Flintshire and he was returned unopposed at general elections in 1761, 1768, 1774, 1780, 1784, 1790 and 1796.

[4] Mostyn was a Whig whose voting record became a concern to his constituents, and in 1784 his brother-in-law, Thomas Pennant of Downing, threatened to create an opposition although nothing came of it.

[4] Mostyn died on 26 July 1796, "much regretted and esteemed for his many public and private virtues".