Prince William Victor Charles Augustus Henry Sigismund of Prussia (German: Wilhelm Viktor Karl August Heinrich Sigismund; 27 November 1896 at Kiel – 14 November 1978 at Esparza, Costa Rica), was the second son of Prince Henry of Prussia and his wife, Princess Irene of Hesse and by Rhine.
He was a nephew of Kaiser Wilhelm II and Tsarina Alexandra of Russia.
A great-grandson of Queen Victoria through both his parents, he was the only one of three brothers who did not have the hemophilia common among her descendants.