Guy X de Laval

Guy X de Laval (c. 1300–1347) was a Breton baron, lord of Laval and Vitré. In 1315 he married Béatrix of Brittany, daughter of Duke Arthur II, which made Duke John III his brother-in-law. Their children included Guy XI, Jean, later Guy XII, and Catherine, who in 1361 married the constable Olivier de Clisson.

On 18 June 1347 he fought at La Roche-Derrien in the Breton War of Succession, the battle in which Charles of Blois was taken prisoner. Guy X was killed there, and his son Guy XI, fighting beside him, was captured.