Guillaume de Sonnac (died 6 April 1250) was Grand Master of the Knights Templar from 1247 to 1250.
Personal life
Sonnac was born to a noble family in the French region of Rouergue. No date of birth survives for the Grand Master. He was described by Matthew Paris as "a discreet and circumspect man, who was also skilled and experienced in the affairs of war".
De Sonnac was an established member of the order before his election as Grand Master. He was the Preceptor of Aquitaine in France for the Templars and arrived in the Holy Land around autumn of 1247, finding "the remnants of the Kingdom of Jerusalem in a precarious state. They targeted Damietta, just as the Fifth Crusade had years earlier. Fighting on the Egyptian beaches was heavy and the King fought in waist-high water alongside the troops. However, another source, Matthew Paris, reported that de Sonnac was forced into the assault by the Count. Robert was "bellowing and swearing disgracefully as is the French custom", and blaming the Templars and other religious orders for causing the real downfall of the Kingdom. Disgusted, de Sonnac returned to his men and prepared to chase down the numerically superior enemy.
In fiction
Guillaume de Sonnac is a prominent character in Crusades, a graphic novel by Izu, Alex Nikolavitch, and Zhang Xiaoyu, published by Les Humanoïdes Associés, in which he is shown as a power hungry plotter.