Who was the fiercest mongol leader of all time?

The fiercest Mongol leader of all time is widely considered to be Genghis Khan, who united the Mongol tribes and founded the Mongol Empire in the early 13th century. His military strategies, innovative tactics, and ruthless conquests allowed him to expand the empire across Asia and into Europe, creating one of the largest empires in history. Genghis Khan's legacy is marked by both his brutality in warfare and his contributions to trade and culture across the regions he conquered.