Brian Blessed: Caesar Augustus, first Emperor of Rome and founder of the Roman Empire

As you can see from the photo above, Brian Blessed is a monster performer. Check his genre credential highlights:
Flash Gordon (1980)
High Road To China (1983)
Kenneth Branaugh's Henry V (1989)
Robin Hood: Prince of Thieves (1991)
Star Wars: Episode I - The Phantom Menace (1999)
Mind you, these are just the highlights. Blessed is down for his crown, no questions asked.