Sir John Penington (1584?–1646) was an English admiral who served under Charles I of England.
John Penington was the second cousin of Sir Isaac Penington or Pennington, and the son of Robert Penington of Henham in Essex, described as a tanner. He is said to have been baptised at Henham on 30 January 1568; but the circumstances of his later career, and the fact that he is unmentioned during the war with Spain or for twelve years after its close, suggest that he was born at a later date. It is possible that he and his half-brother, also John, born in 1584, have been confused together. The Oxford Dictionary of National Biography speculates that on balance his date of birth was 1584.
His name first appears as captain of his own ship, the Star, and vice-admiral under Sir Walter Raleigh in the voyage to the Orinoco in 1617. He remained with Raleigh at the mouth of the river; but putting into Kinsale, on the way home, the ship was seized by order of the Lord Deputy of Ireland, and in London he himself was thrown into prison. In a petition to the council he stated that he had lost £2,000, his whole property, in the voyage; now his ship was taken from him; not having been at St. Thomas's, he could give no information as to what had been done. He gave evidence, however, that Raleigh had 'proposed the taking of the Mexico fleet if the mine failed'. Raleigh, writing from Saint Kitts on 21 March 1617–18, described him as 'one of the sufficientest gentlemen for the sea that England hath'. His imprisonment does not seem to have been long, and during the latter months of 1618 and through 1619 he was applying to the East India Company for employment, with a recommendation from the Duke of Buckingham. His applications were unsuccessful, and in 1620 he was in the service of the crown as captain of the Zouch Phœnix, in the expedition against Algiers under Sir Robert Mansell.