This is a great question. Hannibal was the son of Hamilcar Barca and lived from 247 -183 BC. He was the greatest Carthaginian general and the fiercest foe that Rome has arguably ever faced, at least during the Republic.
He is best known for his daring attack on the Romans on their soil. He marched an army, which also included elephants, over the Pyrenees into Northern Italy. What was more impressive though was his defeat of several Roman consular armies. He defeated the Romans on three occasions at Trebia, Trasimene, and Cannae. The last of these was a devastating blow, which the Romans never forgot.
In addition, to these victories, Hannibal was able to gain local support to further threaten the Romans. In short, Hannibal nearly became master of Rome.
He is also known for a famous oath that he made as a boy always to be an enemy of Rome. One source reports that Hannibal told his father, "I swear so soon as I am old enough...I will use fire and steel to destory the destiny of Rome."
Fortunately for Rome, Hannibal was defeated by Scipio Africanus at the Battle of Zama.