[Falcao]

Wow thanks, computer science school finally paid off

I hope this is not too obscure, but I'm thinking about an Eastern Roman Emperor who got his nickname after he won a great victory over an ancient people.

If you want a first hint:

Spoiler:

This ancient people is now an European country.

*** EDIT ***
Maybe it is too obscure, so there is a second hint:

Spoiler:

His regal family shares the name with the home country of a famous Greek conqueror who is one of the "nine worthies"

If nobody is interested I will give the answer the next time I log-in (i.e. 5/6 hours from now). You can check what time is "now" in the lower part of this post).