Assassin's Creed: Valhalla - 10 Real-Life Viking Legends Who Should Appear

Possibly most famous today for having a wireless technology named in his honor, Harald Bluetooth was nevertheless an important figure in history, a king who briefly united Denmark and Norway, introduced Christianity and was famed for his efficiency as a ruler, building fortresses, improving Denmark's infrastructure and carefully managing diplomatic relations with other countries at a difficult time.

His religious conversion didn't sit well with everybody, however, and he was eventually overthrown by his own son, Sweyn Forkbeard.