Cornelis Evertsen the Elder (4 August 1610 – 11 June 1666) was a Dutch admiral.
Cornelis Evertsen the Elder was the son of Johan Evertsen and Maayken Jans; grandson of Evert Heindricxsen, a Watergeus, both commanders of men-of-war of the navy of Zealand.
When his father was killed in battle in 1617, the Admiralty of Zealand appointed all five of his sons as Lieutenant, including Cornelis (or Kees) and his oldest brother Johan, despite their young age. This exceptional favour was granted in recognition of the great merits of the father and of course prevented his family from becoming destitute.
In 1626 Cornelis is first mentioned as actually serving on sea, during a privateering raid. On 25 August 1636 he was appointed captain. In the Battle of the Downs in 1639 he captured a galleon.
During the First Anglo-Dutch War Cornelis functioned as a Vice-Commodore in the Zealandic navy; he was appointed on a confederate level to the equivalent rank of temporary Rear-Admiral on 1 May 1652. In the Battle of Scheveningen his ship sank and he, wounded, was prisoner of the English for three months.
On 14 March 1654 he was appointed Rear-Admiral. During the Northern Wars he was in 1659 subcommander of the fleet of Michiel de Ruyter and liberated Nyborg from the Swedish. In 1661 he was third in command of the Dutch Mediterranean fleet under De Ruyter, executing punitive actions against the corsairs of Algiers. He and De Ruyter were close personal friends.
When the Second Anglo-Dutch War threatened, he was made Vice-Admiral of Zealand, while his brother Johan Evertsen was promoted to the first Lieutenant-Admiral that province ever had. Cornelis Evertsen took part in the Battle of Lowestoft (13 June 1665); his elder brother was after the fight much criticised for his behaviour and had to resign as commander, though keeping his rank. Cornelis was now promoted to Lieutenant-Admiral also, so that for a time the Dutch navy had seven officers of this rank.