Alexander IV (323–309 BC), posthumous son of Alexander the Great and his wife Roxana of Bactria. Soon after he was born, the infant Alexander joined Philip Arrhidaeus as joint ruler of Alexander's empire while Perdiccas served as regent. He remained insignificant until 317, when his grandmother, Olympias, used him in the power struggle to control Macedon. Alexander and Olympias fell into Cassander's hands in the spring of 316 and were interned at Amphipolis until he was murdered and secretly buried. See here for a more detailed biographical sketch.