Guy XII de Laval

Guy XII de Laval (c. 1327–1412), second son of Guy X and Béatrix of Brittany, was baptised Jean and took the name Guy only in 1348, when he succeeded his brother Guy XI as lord of Laval and Vitré. He stood close to Bertrand du Guesclin and to Olivier de Clisson, his brother-in-law from 1361.

After Auray in 1364, du Guesclin was captured and his ransom set at 100,000 livres; Charles V raised 40,000 and Guy paid the rest. In 1370 he was among the commanders who beat Robert Knolles' English at Pontvallain.

He helped broker the second Treaty of Guérande in 1381. In 1384 he married du Guesclin's widow, Jeanne de Laval; their daughter Anne inherited Laval and Vitré when he died in 1412.