Philadelphus

Also known as: Ptolemy · Family: Egyptian · Role: king of Egypt · First appears: Book 1 · Chapter 7

In Book 1, Chapter 7, Ptolemy married his sister Arsinoe. He also slew his brother Argæus for plotting against him, brought Alexander’s corpse from Memphis, and faced a revolt led by his uterine brother Magas, who marched from Cyrene toward Egypt. Magas then persuaded Antiochus to break the conditions made with Ptolemy and invade Egypt; Ptolemy sent troops into Antiochus’ dominions and checked his forces, preventing the invasion.

Arsinoe predeceased Ptolemy and was childless. Book 9, Chapter 31, also records a statue of her at Helicon and notes that Ptolemy married her despite their being siblings.