Amalasuntha ruled Rome after the Roman Empire's fall. She is known for being a wise leader of the Ostrogoths, first as regent, then as the ruling monarch.
Boudica, Queen of the Iceni, is famous for completely humiliating the Roman Empire. Her and her revolt are probably the most famous events of Roman Britain.
Once upon a time, when the Roman Empire was falling apart, a warrior Queen nearly defeated the Romans. I'm not even joking, this actually happened.