Robert Knox (8 February 1641 – 19 June 1720) was an English sea captain in the service of the British East India Company.

Born at Tower Hill in London, the young Knox spent most of his childhood in Surrey and was taught by James Fleetwood, later the Bishop of Winchester.

They suffered the loss of the ship's mast in a storm on 19 November 1659, forcing them to put ashore on Ceylon, now Sri Lanka.

The ship was impounded and sixteen of the crew, including the Knoxes, were taken captive by the troops of the ruler of Kandy, Rajasinghe II.

Although the crew was forbidden from leaving the kingdom, they were treated fairly leniently; the younger Knox was able to establish himself as a farmer, moneylender and pedlar.

It attracted widespread interest at the time and made Knox internationally famous, influencing Daniel Defoe's Robinson Crusoe as well as sparking a friendship with Robert Hooke of the Royal Society.