The founder of the Mongol Empire was:

The question identifies the founder of the Mongol Empire. Genghis Khan (born Temüjin) is the correct answer. He was the founder and first Great Khan of the Mongol Empire, which became the largest contiguous empire in history after his death. He unified many of the nomadic tribes of Northeast Asia and launched the Mongol invasions that conquered vast areas of Eurasia in the early 13th century.

• Kublai Khan was a grandson of Genghis Khan and founded the Yuan Dynasty in China.
• Timur (Tamerlane) was a Central Asian conqueror who founded the Timurid Empire in the late 14th century, much later than the Mongol Empire.
• Attila the Hun was the leader of the Huns, active in the 5th century, long before the Mongol Empire's formation.