As we are about to have the Grand Berserker duel released, I was pondering, we actually have very little in terms of some pretty legitimate, actual Berserkers according to the precise definition of the term, nevermind the bonafide article such as Berserkers from Norse sagas, the material where they're actually from.

The coronation and celebration of the class is coming soon and we still lack a truly shining example that epitomizes the class itself. Instead, over the years the class became an excuse to give pretty much any given servant a semi-universal and favorable damage modifier with barely any compelling character or lore justification. And on a different issue, the lack of speech that has been associated with some early servants of the class has made them hard to develop, write and interact with in the mobile game format vs how several of these characters tended to stand better in the previous VN or anime formats.

Now, I think Bodvar Bjarki would have been a fantastic actual and legitimate Berserker from the Norse sagas to have on the stable and give the game and the series that shining example it still lacks, that epitome of what a Berserker truly is, from its root sources.

https://en.wikipedia.org/wiki/B%C3%B6dvar_Bjarki

His heroic biography is stacked, and in the final epic battle of 'Hrólfs saga kraka' he goes into a trance where he turns himself, or projects from his being, an actual fearsome bear that swats warriors with his paws across the battlefield.

He also has some interesting connections with Beowulf and seems to be an inspiration for Tolkien's Beorn from The Hobbit.

Alternatively, and a bit more from an obscure interpretation, the sired avenger Vali (son of the already in-game Valkyrie Rindr and who could also be an Archer as well) might be considered an 'Ulfheonar' at some point with the blessing of Odin, as he turns himself into a wolf and tears apart one of Loki's son, using his intestines to bind Loki on a rock for his punishment.