Sir John Harington (4 August 1560 – 20 November 1612), of Kelston, Somerset, England, but born in London, was an English courtier, author and translator popularly known as the inventor of the flush toilet.

He was the author of the description of a flush-toilet forerunner installed in his Kelston house, appearing in A New Discourse of a Stale Subject, called the Metamorphosis of Ajax (1596), a political allegory and coded attack on the monarchy which is nowadays his best-known work.

Although he had studied the law, Harington was attracted early in life to the royal court, where his free-spoken attitude and poetry gained Elizabeth's attention.

It was a coded attack on the stercus or excrement that was poisoning society with torture and state-sponsored "libels" against his relatives Thomas Markham and Ralph Sheldon.

After her strong recommendation that Essex include him in his army, Harington was put in command of horsemen under Henry Wriothesley, 3rd Earl of Southampton.

Harington wrote: "I have informed myself reasonably well of the whole state of the country, by observation and conference: so I count the knowledge I have gotten here worth more than half the three hundred pounds this journey hath cost me."

[16] Harington, present at the truce negotiations, accompanied Essex back to court to account to Elizabeth, but met with royal wrath: "Tell my witty godson to get him home ... it is no season to fool it here!"

Elizabeth thanked him, but said sadly, "When thou dost feel creeping time at thy gate, these fooleries will please thee less – I am past my relish for such matters".

[18] He claimed to be unhappy at James's court, owing specifically to the heavy drinking by both sexes, but in fact, he seems to have derived amusement from the antics of the courtiers.

He left a description of a disastrous attempt by Sir Robert Cecil to stage a masque at Theobalds in honour of a visit by the King's brother-in-law, Christian IV of Denmark in 1606, when some of the players were too drunk to stand up: "The entertainment and show went forward, and most of the presenters went backward, or fell down, wine did so occupy their upper chambers.