Lawrence Kemys or Keymis (died 1618) was a seaman and companion of Sir Walter Raleigh in his expeditions to Guiana in 1595 and 1617-18.
Raleigh's 1596 voyage to Trinidad and Guiana consisted of two vessels, with Kemys serving as second-in-command and captain of the second ship. The aim of the expedition was to find El Dorado and to strike up friendly relations with native tribes. Upon reaching Guiana, Kemys led a force inland along the banks of the Essequibo River, reaching what he wrongly believed to be Lake Parime.
The next year, 1596, Raleigh being unable to go himself, sent Kemys in command of the Darling to continue the exploration of the Guiana coast and the Essequibo river. Kemys brought back glowing accounts of the wealth of the country he had visited, and urged on Raleigh that it would be greatly to the advantage of the queen Elizabeth I to take possession of it. Raleigh, however, was not in a position to follow the advice, and Kemys seems to have remained in his service on shore.
When, in 1603, Raleigh was accused of devising the so-called Main Plot against the King James I, Kemys, as his follower and servant, was also implicated, and was imprisoned with him in the Tower of London, and afterwards in the Fleet, September– December 1603. He was probably released at the end of the year, and during Raleigh's long imprisonment of thirteen years, seems to have acted as his bailiff and agent.
In 1617, Raleigh was pardoned by the King James I and it was no doubt that Kemys instigated Raleigh to demand the Royal permission to go on his last voyage to the Orinoco, and when the permission was at last granted, Kemys accompanied him as pilot and captain, claiming to have certain knowledge of a rich gold mine.
Kemys again sailed with Raleigh to Guiana in 1617, in search of gold with which Raleigh hoped to buy back royal favour. Kemys was unintentionally instrumental in the sequence of events that led to the final downfall and execution of Raleigh after leading a party of Raleigh's men in an attack on the Spanish outpost of Santo Tomé de Guayana on the Orinoco River, against Raleigh's orders, and in violation of peace treaties signed by the King, James I, with Spain. Raleigh's son Walter was killed during the attack. A condition of Raleigh's release from the Tower of London in 1616 to undertake his mission to Guiana in search of gold deposits and the legendary city of El Dorado had been that he not attack or harass Spanish colonies or shipping. As Raleigh had been under a suspended death sentence for treason since 1603, the fact that men under his command had violated this order meant that James I would have had little option but to enforce this earlier sentence.