John Ashburnham (1603 – 15 June 1671) was an English courtier, diplomat and politician who sat in the House of Commons at various times between 1640 and 1667. He supported the Royalist cause in the English Civil War and was an attendant on the King.
Ashburnham was the eldest son of Sir John Ashburnham by Elizabeth, daughter of Sir Thomas Beaumont. His father was a wastrel and died in 1620, but his mother was related to Lady Villiers, mother of George Villiers, 1st Duke of Buckingham. Under Buckingham's patronage Ashburnham became well known to the king Charles I, who styled him 'Jack Ashburnham' in his letters. In 1628 Ashburnham became groom of the bedchamber.
Ashburnham became wealthy and lent money to the king: in 1638 the Star-chamber fine on Sir Walter Long, 1st Baronet and his brother, was assigned to Ashburnham. The next year a warrant under the privy seal enabled him to regain his ancestral estate of Ashburnham. He sat as a Member of Parliament for Hastings in the Long Parliament in 1640. As a partisan of the king, he began to absent himself, and he was proceeded against for contempt (6 May 1642). The king wrote a letter to the Commons in his justification but the house maintained its prior right to the obedience of its member. Ashburnham was 'discharged and disabled' (5 February 1643), and his estate was sequestrated (14 September).
Ashburnham was a faithful adherent and attendant to Charles I in the First English Civil War, and "became the treasurer and paymaster of the king's army... His name occurs in seven negotiations for peace. He was one of the commissioners at the Treaty of Uxbridge (1644), and one of the four appointed to lay the king's proposals before parliament (December 1645). When Thomas Fairfax prepared to besiege Oxford, and Charles determined upon flight, Ashburnham and Michael Hudson were the sole attendants to the king in his... journey [in 1646] to the Scottish camp. Hudson was released, and Ashburnham was positively commanded by the king to flee before confirmation of the order to send him up to London as a delinquent could be received. He made his way safely to Holland, and thence to Queen Henrietta Maria at Paris."