German king from Oct. 3, 1247, elected by the papal party in Germany as antiking in opposition to Conrad IV and subsequently gaining general recognition. As William II he was also count of Holland, succeeding his father, Count Floris IV, in 1234.

William was elected German king to succeed Henry Raspe (died Feb. 16, 1247), Pope Innocent IV's nominee to replace Conrad, whom the Pope had declared deposed in 1245. Although crowned at Aachen on Nov. l, 1248, William was king of a minority of the German states until King Conrad decided, late in 1251, to leave Germany for Italy (where he became king of Sicily). On March 25, 1252, William was recognized as king by Albert, duke of Saxony, and by John and Otto, margraves of Brandenburg; further support came in 1254, from the Rhenish League of Cities.

William's growing strength in the Rhineland caused Archbishop Conrad of Cologne (who had crowned him) to plan his deposition in favour of Otakar II of Bohemia. That conspiracy (late 1254) was checked by Pope Alexander IV.

As count of Holland, William promoted the urban development of Haarlem, Delft, Middelburg, and Alkmaar, all of which became trading centres. While trying to secure his rule over the Frisians, he was killed in battle.