thumb|right|John Ashburnham around 1630, portrait by [[Daniel Mytens.]]
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.
Background
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).
Commonwealth period
Subsequently, the Commonwealth authorities detained Ashburnham in the Tower of London and three times banished him to the Channel Islands. His second wife was the widow of Lord Poulet of Hinton St. George.
Ashburnham's daughter Elizabeth married Sir Hugh Smith, 1st Baronet of Long Ashton. His grandson John was ennobled as Baron Ashburnham in 1689, and his great-grandson as Earl of Ashburnham, a title that became extinct in 1924.