Ptolemy IX Soter II (ca. 143–81 bc). Also known as Ptolemy Lathyrus. Older son of Ptolemy VIII Physcon and Cleopatra III and brother of Ptolemy X Alexander; ruler of the Ptolemaic dynasty in Egypt from 116 to 107 bc and again from 88 to 81 bc.

Upon his father’s death, Soter II was made coregent with his mother only because the people of Alexandria, Egypt, demanded it. Cleopatra III wanted her younger son, Alexander, to be king instead. Twice during Soter II’s reign, his mother temporarily replaced him with his brother, and in 107 bc she permanently deposed him. He fled to Cyprus, where he ruled from 107 to 88 bc.

When Hasmonean high priest-king Alexander Jannaeus besieged Ptolemais (Acco) along the Mediterranean coast, Soter II came from Cyprus to prevent Janneus’ success. The two then made an alliance in which Janneus said he would help Soter II conquer Egypt in return for his help conquering Phoenicia. However, Jannaeus revealed the plan to Cleopatra III. When Ptolemy IX learned of the betrayal, he invaded Judea, destroyed towns, and slaughtered Jews. Cleopatra’s army put an end to his rampage, forcing Soter II back to Cyprus.

When his younger brother, Alexander, was expelled from Egypt and then killed in battle (88 bc), Soter II reclaimed the throne until his death (81 bc).