Basil Argyros is the eponymous main character of a sequence of short stories (by Harry Turtledove) set in an alternate 13th Century. In this universe, the Prophet Muhammad, instead of developing Islam, converts to Christianity. As such, by the time the stories take place, the Eastern Roman Emperor is still the pre-eminent power in the Mediterranean world, and has reconquered much of Europe and Africa.

Basil works as an agent for the Roman Emperor, and as such is sent across the Empire to solve problems - sometimes as a spy, sometimes as a negotiator, and sometimes as a soldier.

Stories in the Basil Argyros universe (in order written) are:

• Unholy Trinity
• Archetypes
• The Eyes of Argos
• Strange Eruptions
• Images
• Superwine
• Pillar of Cloud, Pillar of Fire

Most of the above were collected into a single book, Agent of Byzantium. An additional story in the universe, Departures, was written by Turtledove; Basil was absent from it as it took place hundreds of years earlier, and focused on the future St. Mohammed.