Born in Alexandria around 69 BCE to the Greek-descended dynasty of Ptolemy, Cleopatra took over Egypt once her father was gone [source: History]. To shore up allegiances, she became the mistress of Julius Caesar, and bore him a son. Meanwhile, Caesar's friend Mark Antony was having his own drama: He was high-born, but frittered away his youth. When a friend died, he took the man's wife, Fulvia, as his own. Later, he ran to Greece to avoid the debts he'd racked up in Rome, but eventually joined the military, where his connections to Caesar -- and Octavian, a later Roman ruler -- were very helpful in his career.
When Julius Caesar was assassinated, Antony joined a triumvirate of leaders over Rome. Reaching out to Cleopatra, he was denied an audience with her twice before they met -- and fell in love. He married her in Egypt, forming a new political allegiance and freaking out Fulvia, who staged an attack on Octavian to smear Antony's name. Mark Antony ran home to Fulvia, but it was too late to salvage things -- Fulvia died soon after. To try and smooth the debacle over, Antony married Octavian's sister to unite their families.
So now it was Cleopatra's turn to hear about his deeds -- and she was just weeks from delivering twins! But she was a princess and a savvy politician, so she kept supporting his army. And then, once Octavian proved dubious as an ally, Antony divorced the (pregnant!) sister, and returned to Egypt. Enraged, Octavian used this as a chance to attack Egypt and consolidate power, which is when things get unbelievable.
Scared for her life, Cleopatra started rumors that she was dead, and hid out in her burial crypt. Unfortunately, one of the people who believed this gossip was Antony, so -- keep in mind that Shakespeare wrote the definitive fictional account of this, so this part might be familiar -- he killed himself. Distraught, and certain Octavian would eventually take her prisoner in his conquest of Egypt, Cleopatra followed suit [source: McManus].
No wonder it's the most famous affair of all time. It's got everything! Including the fact we sometimes forget, which is that when you're looking at historical rulers -- from Alexander the Great up through the Tudors -- you're also looking at empires that covered the entire known world. The love affairs of Cleopatra are tabloid fodder to our eyes, but we can't forget that every war, for these guys, was a world war.