Willem van der Zaan (29 June 1621 – 17 March 1669) was a Dutch Admiral. His name is often given in the 17th century spelling Zaen.
Willem was born in Amsterdam. He joined the Dutch navy at a young age and had risen to the rank of captain by 1652. He took part in the First Anglo-Dutch War from 1652–1654, fighting in the Battle of Dungeness on the Prinses Aemilia, and on the Campen (after the previous captain, his brother Joris van der Zaan, had been killed in the Battle of Portland; in the same battle his other brother, Huybrecht van der Zaan, was killed also) in the Battle of the Gabbard and the Battle of Scheveningen. In 1655 he was made a full captain. In 1656 he commands the Zuyderhuys, having on board his nephew, the son of Huybrecht, Cornelis van der Zaan, later a captain also. In 1657 he participated in an action in the Mediterranean under Vice-Admiral Michiel de Ruyter, during which he captured the French warship Chasseur, caught while illegally privateering, causing much embarrassment to the French government that had given secret orders to do so. Cardinal Mazarin summoned the Dutch ambassador to ask for excuses, who then lost his temper and left the court in a fury after telling the good cardinal, the most powerful man of France, in his face that he was no better than a common pirate. The States-General showed their opinion on this by awarding Van der Zaan a golden honorary chain. In 1658 he fought against Sweden in the Battle of the Sound, again participating in actions in the Baltic in 1659 and 1660, as captain of the Huys Tijdverdrijf. In 1661, as captain of the Middelburg, he is again with De Ruyter in the Mediterranean. When the Dutch fleet is challenged by the Bey of Algiers, Suleiman Basha Reis, to provide a champion for a ship duel, De Ruyter chooses Van der Zaan as such; but the Algerian champion didn't show up. That year Van der Zaan received another golden chain for capturing a corsair liberating 36 Christian slaves; in 1663 a third one having taken a privateer with 21 Christian slaves on board.