Cornelius Jacobszoon Drebbel (Alkmaar, 1572 - London, November 7, 1633) was a Dutch inventor.

Drebbel only had elementary education; he had no university education. In 1604, King James I of England received Drebbel at his court in England.

He is chiefly famous for his invention, in 1619, of a microscope with two convex lenses. It was the first microscope with two lenses ever invented.

He also built the first navigable submarine in 1620 while working for the British Navy. This submarine was tested many times, but never used. Between 1620 and 1624 Drebbel successfully maneuvered at depths of from 12 to 15 feet (4 to 5 metres).

Drebbel's most famous work he wrote was Ein kurzer Tractac von der Natur der Elemetum (Leiden, 1608).

Drebbel was recently exalted on an episode of the cartoon Sealab 2021 during a rescue operation by submarine of workers on a research station in the Arctic. A German U-boat captain, who mysteriously "came with the sub" fired a pistol in celebration at the mention of Drebbel, to shouts of, "SIEG HEIL! CORNELIUS DREBBEL!"