William the Lion was a Scottish king who ruled from 1165 to 1214. He was the son of Henry, Earl of Northumberland and Ada de Warenne. William is known for his efforts to strengthen the Scottish monarchy and expand its territories. He was captured during a conflict with King Henry II of England and spent several years in captivity. During his reign, William the Lion worked to establish Scotland's independence and improve its governance. He signed the Treaty of Falaise in 1174, which temporarily recognized English control over Scotland. However, he later regained his freedom and continued to promote Scottish interests throughout his rule.