Pothinus
Potheinus (early 1st Century BC - 48 or 47 BC) was regent for Pharaoh Ptolemy XIII of the Ptolemaic dynasty of Ancient Egypt. He is most remembered for turning Ptolemy against his sister and co-ruler Cleopatra VII, thus starting a civil war and for having Pompey decapitated and presenting the severed head to Julius Caesar.
When Ptolemy XII died in 51 BC his will stated that Ptolemy XVIII and Cleopatra VII become co-rulers of Egypt, with the Roman Republic as their guardians. Ptolemy the VII was underage and Potheinus was appointed as his regent. When Ptolemy and Cleopatra were elevated to the status of senior rulers Potheinus was maintained as the former's regent. Most Egyptologists believed that Pothenius used his influence to turn Ptolemy against Cleopatra, and in Spring of 48 BC Ptolemy, under Potheinus guidance, attempted to depose Cleopatra in order to become sole ruler, while Potheinus planned to act as the power behind the throne. They gained control of Alexandria, then the capital of Egypt, and forced Cleopatra out of the city. She soon organized her own army and a civil war began in Egypt, while Arsinoe IV also started to claim the throne for herself.
Rome was also enveloped in civil war and after his defeat in the battle of Pharsalus Pompey sought asylum in Egypt. Initially Potheinus pretended to have accepted his request but on September 29, 48 BC, Potheinus had the general beheaded -- hoping to win the favor with Julius Caesar, who had defeated Pompey. When Caesar arrived he was presented with the head of Pompey, and but he responded with grief and disgust and ordered that Pompey's body be located and given a proper Roman funeral. Potheinus had neglected to note that Caesar had been granting amnesty to his enemies, including Cassius, Cicero, and Brutus and that Caesar was in fact Pompey's father in law. Cleopatra used Potheinus' mistake to help her gain favor with Caesar and eventually became his lover.
Caesar then arranged for the execution of Potheinus and the marriage Cleopatra to Ptolemy.