I heard somewhere that there is an opinion that Binyamin was a werewolf. Do you know anything about this?
It's a thing!
It's derived from this phrase in Parshat VaYechi, the last Parsha in Bereishit (Genesis):
בִּנְיָמִין֙ זְאֵ֣ב יִטְרָ֔ף בַּבֹּ֖קֶר יֹ֣אכַל עַ֑ד וְלָעֶ֖רֶב יְחַלֵּ֥ק שָׁלָֽל׃
"Binyamin is a devouring wolf, in the morning he shall consume his foe, and in the evening he divides the spoils." [Bereisht 49:27]
The Tosafist Rabbi Ephraim ben Shimshon said thus:
"Benjamin was a ravenous wolf, who would occasionally maul people -- and when the time came for him to turn into a wolf, as it says, "Benjamin is a ravenous wolf" (Gen. 49:27), if he was with his father he could rely on a physician, and in that merit would not turn into a wolf. Thus it says, "and if he leaves his father he will die" (Gen. 44:22) -- that is to say, if he separates from his father he will turn into a wolf [and attack] people on the way, and anyone who encounters him will kill him."
[translated from Hebrew by Rabbi Natan Slifkin]
According to Rabbeinu Ephraim, Binyamin was a werewolf. When he was at home, he was able to be controlled or cured by a physician under his father. The reason the brothers were so reluctant to part from Binyamin is because he was a werewolf, and without his father he would become uncontrollable.
Werewolfs were creatures discussed by many Jewish figures throughout history. They were a creature accepted in the "mythological canon", so to say.
....
Regardless.....
The symbol of Binyamin is wolf. It is on his flag. Everyone agrees about that. So take with that what you will.
Here's a collection of writings about this from Sefaria, if you'd like to learn more:
