Willem is the Dutch form of William, from the Germanic Willahelm, and means "resolute protector", from wil, will, and helm, helmet. It is a royal name in the Netherlands, borne by William of Orange and the current king, Willem-Alexander, and Americans know it from the actor Willem Dafoe. In the United States Willem ranked number 1340 in 2000, peaked at number 1208 in 2003 and was given to 51 boys in 2025, placing it at number 2601.