Croesus

Croesus was the king of Lydia from 560 BCE until his defeat by the Persians in 547 BCE. He was renowned for his vast wealth. He campaigned against the Persian empire, and received this statement from the oracle at Delphi before going to war - "If you attack Persia, you will destroy a great empire." This is a classic example of the oracle's ambiguity. He also allied himself with the Spartans. He was eventually defeated by Cyrus at Sardis in 547 BCE, when the Spartans didn't show up in time. Just before Croesus was put to death, Cyrus changed his mind (Herodotus writes about Apollo's intervention), and Croesus became an advisor to the Persian emperor.

Croesus appears in Herodotus.