An Irish term for a mermaid or merman. The usual half-human, gorgeous human waist up and fish-like waist down. They have soft white webbing between their fingers and green hair. They always wear special hats called the cohuleen druith which enables them to dive in the water without having to come out for air.
The Moruidh are known to have a gentle, modest and affectionate personalities that they are capable of inter-marrying with humans. Though there are stories of these intermarriages, they would always go back to sea after a while rather than living happily ever after together.