Antigonus I Monophthalmos ("the One-eyed") was a Macedonian nobleman, general, and governor under Alexander the Great. He was born on 382 BC.
Upon the death of Alexander in 323 BC, he established himself and his family as one of the successor dynasties, the Antigonid dynasty, along with the Seleucids and Ptolemies. He declared himself King in 306 BC, claiming power over the whole of Alexander's Empire. The most powerful Satraps of the Empire, Cassander, Seleucus I Nicator, Ptolemy I of Egypt and Lysimachus, answered by proclaiming themselves Kings and their territories Kingdoms. This resulted in wars between them. With Antigonus's death in battle against them in 301 BC his plans of reuniting Alexander's Empire came to an end. The victors did not claim power over each other, but rather accepted their Kingdoms as separate.