Explanation: Roman Emperors first had the Praetorian Guard, Roman soldiers/secret police, as a full-time bodyguard in civilian life. Previous Roman magistrates had Lictors to accompany them - ceremonial guards with sticks and axes representing the power of life and death. Later Roman and Byzantine Emperors turned to barbarians to protect them - the most famous Byzantine bodyguards being the Varangian Guard, which was made up mostly of Germanic and Slavic mercenaries. Funny enough, they were some of the most reliable of the lot - foreigners don't have local loyalties to your court enemies!