Ptolemy of Mauretania (Ancient Greek: Πτολεμαῖος}}, Latin: Ptolemaeus, 1 BC-40) was a prince and the last Roman client King of Mauretania.

Ptolemy was the son of King Juba II and Queen Cleopatra Selene II of Mauretania. He had a younger sister called Drusilla of Mauretania. His father Juba II was the son of King Juba I of Numidia, who was descended from the Berber people of North Africa and was an ally to the Roman Triumvir Pompey. His mother Cleopatra Selene II was the daughter of the Ptolemaic Greek Queen Cleopatra VII of Egypt and the Roman Triumvir Mark Antony. Ptolemy was of Berber, Greek and Roman ancestry. Ptolemy and his sister Drusilla were the only children of Juba II and Cleopatra Selene II and were among the younger grandchildren to Mark Antony. Through his maternal grandfather, Ptolemy was distantly related to Julius Caesar and the Julio-Claudian dynasty. Ptolemy was a first cousin to Germanicus and the Roman Emperor Claudius and a second cousin to the Emperor Caligula, the Empress Agrippina the Younger, the Empress Valeria Messalina and the Emperor Nero.