Which Greek mythological hero had his power in his hair?

Answer 1

Sadly I don't know his name, but there was one King or Lord who was fighting against Minos of Crete and he had his power in his hair, which was then cut off by his daughter Scylla who loved Minos, leading to his defeat

You seams to be thinking of Nisos.

If gender is not a major factor then Medusa... poor gal

some symbolism within the Illiad conserns Achilles hair as the seat of wisdom and reticence which was a major factor in his battle tactic.

one piece is within the first few pages of the Illiad when he is about to kill Agamemnon and Grey eyed Athena comes and holds him back by his hair, saying the fates have worse things planned for Agamemnon. So Achilles retreats and simply plays klea androns glories of men. This is a metaphorical power and speaks of the power of humanity. This is not any sort of mystical power.

Answer 2

On second look at this, I realize that you may not be talking about a Greek god, but about the biblical character in the Old Testament named Samson from the story of Samson and Delilah. In this, two countries are warring with each other. Samson is a man who's strength is a gift from God, however his strength comes from his hair. Delilah seduces Samson into tell him where his power comes from, so when he's sleeping she cuts it off, thus removing his superior strength. Delilah turns him in to the enemy where they chain him to two pillars and ridicule him every night. Unfortunately for them, they forgot to count on his hair growing back!