Ptolemy IX Soter II or Lathyros (Greek: Πτολεμαίος Σωτήρ Λάθυρος) was king of Egypt three times, from 116 BCE to 110 BCE, 109 BCE to 107 BCE and 88 BCE to 81 BCE, with intervening periods ruled by his brother, Ptolemy X Alexander.
At first he was chosen by his mother Cleopatra III to be her co-regent (his father Ptolemy VIII wished that she would rule with one of her sons), though she was more forced to choose him by the Alexandrians. He married his sister Cleopatra IV, but his mother pushed her out and replaced her with his younger sister Cleopatra Selene. Later, she claimed that he tried to kill her, and successfully deposed him, putting her favorite son Alexander on the throne as co-regent with her. However, she later grew tired of the now Ptolemy X and deposed him, putting Ptolemy IX back on the throne. She was soon murdered by Ptolemy X, who took the throne again. He was then killed in battle, and Ptolemy IX reigned until his own death.
His daughter Berenice III took the throne after his death, and reigned for about a year. She was forced to marry her stepson Alexander, who reigned under the name Ptolemy XI Alexander II and had her killed 19 days later.
Ptolemy IX's name recalls that of his great ancestor, Ptolemy I Soter; note that in older references, he may be numbered VIII.
- Ptolemy Soter II at LacusCurtius — (Chapter XI of E. R Bevan's House of Ptolemy, 1923)
| Preceded by:|
Ptolemy VIII Physcon
| Ptolemaic King of Egypt|
with Cleopatra III and Cleopatra IV
| Succeeded by:|
Ptolemy X Alexander I and Cleopatra III
|Ptolemy X Alexander I and Cleopatra III|| Ptolemaic King of Egypt|
|Ptolemy X Alexander I|
|Ptolemy X Alexander I|| Ptolemaic King of Egypt|