William of Montferrat, Count of Jaffa and Ascalon

William Longsword of Montferrat ( ital: Guglielmo Lungaspada, lat: Willelmus Longaspatha, * 1135-1145, † 1177 ) was a Count of Jaffa and Ascalon in the Kingdom of Jerusalem.

He was the eldest son of William V († 1191 ), Margrave of Montferrat from the house of Aleramiden and Judith of Austria from the house of Babenberg thus great-grandson of the emperor Henry IV. He was the older brother of Conrad and Boniface and Rainer.

The ordinal number " VII " was not assigned to him, because he would have been the seventh Marquis of Montferrat named William, but because he is the seventh bearer of the name William in the House of Aleramiden. Wilhelm Longaspatha died before his father. He is the son of William V isolated as William VI. counted. His father William V is the sixth Wilhelm from house of Aleramiden as William VI. counted.

In 1176 he was probably on a proposal from King Louis VII of France, King Baldwin IV of Jerusalem and its regent Count Raymond III. Tripoli chosen as a husband for Baldwin's eldest sister Sibylle. Baldwin IV was childless and was suffering from leprosy, which is why it was foreseeable that Sibylle and out of her right and her husband would inherit the throne of the Kingdom of Jerusalem. In October 1176 he reached Sidon and married Sibylle. Due to his marriage William was invested with the traditionally the crown prince entitled County of Jaffa and Ascalon. To the throne by Wilhelm did not happen, because it already, died shortly after the wedding, at the latest in 1177 from malaria. However, Sibylle was pregnant at that time with William's son, the future King Baldwin V.

His widow married in 1180 the western French nobleman Guy of Lusignan, who was he invested with Jaffa and Ashkelon, and finally in 1186, rose to become King of Jerusalem.