William VII of Montferrat

William VII (c. 1240 – 6 February 1292), called the Great Marquess (Italian: il Gran Marchese), was the twelfth Marquess of Montferrat from 1253 to his death. He was also the titular King of Thessalonica.

William was born in Trino, the eldest son of Boniface II and Margaret of Savoy. He was named his father's heir in a testament of 1253, the year of his father's death and his succession. He remained under his mother's regency until 1257. Upon attaining his majority, he married Isabella, daughter of Richard de Clare, in 1258. William's mother was a first cousin of Eleanor of Provence, queen consort of England, and it was through the latter's influence that the marriage was arranged.

In his first years, William looked to exert his power in the southern Piedmont, as many of his predecessors had tried, fighting the independence of the communes of Alessandria and Asti. William sought alliance and support from the Kingdom of France and the Roman Catholic Church. However, his relationship and proximity to the Holy Roman Emperor left him at odds with the Ghibellines. His anti-imperial, pro-French, Guelph policy left him not insignificant problems concerning the imperial authority and his imperialist neighbours.

His participation in Guelph politics and the planned invasion of Lombardy with Charles I of Naples, caused a war with Oberto Pelavicino, the chief Ghibelline commander in the region, in 1264. William resisted him with determination and effectiveness, occupying the fortresses of Acqui Terme, Tortona, and Novi Ligure, and affirming his hold on Nizza Monferrato. In 1265, French reinforcements arrived. Less than eight years from his accession, William had extended his power to Lanzo and the vicinity of Alessandria.

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