Holly Mackerel

Holly Mackerel is a mermaid from The Adventures of Super Mario Bros. 3 episode The Ugly Mermaid. She is the princess of the underwater land of Mertropolis, and the daughter of King Mackerel. During the episode, Mario is entombed in concrete by King Koopa and drowns by being sent to the sea floor, but is saved by Holly, who takes him to Mertropolis.

Princess Toadstool, Luigi and Toad follow them. After rescuing Mario, Holly falls in love with him, mistaking him for a frog prince. Her name is a pun on "Holy Mackerel."

Unlike traditional depictions of mermaids, she has female human legs and a fish's head and torso.