Mermaids and mermen are beautiful creatures with the heads and torsos of humans with tails of fish. Like fairies, mermaids range widely in color and they can have hair colors a human would not have, like Nori's blue hair. They have endless types of tails with sparkling scales that are brightly and colored, with ornate and detailed patterns like flowers and spirals adorning their scales. Mermaids can also be tattoed with the Courage Crest on their arms if they reach the Depths of Despair.
- Fairies can turn themselves into mermaids by going to the Depths of Despair. They can revert back to fairies by eating the True Self berry.