Mermen are mythical male legendary creatures who are human from the waist up and fish-like from the waist down. They are less commonly known than their female counterparts, mermaids.

In Finnish mythology, a merman (vetehinen) is often portrayed as a magical, powerful, handsome, bearded man with the tail of a fish. He can cure illnesses, lift curses and brew potions, but he can also cause unintended harm by becoming too curious about human life.