Berzerker

A berzerker is a specialized warrior whose main attribute is rage. Working themselves into a bloodthirsty frenzy, berzerkers enter battle oblivious to pain and their own personal safety. Vikings commonly used them.

The are usually armed with swords, spears, or axes, and can wear wolf pelts on their heads.

In the game Rome: Total War, Germania has berzerker units. In the right context, they can disrupt a Roman legion. However, against a well-prepared phalanx formation, they are relatively useless.