wereshark

plural weresharks

1. fantasyA shapeshifter that can transform from a human to a shark or shark-like creature.

   Several nonmammalian creatures are worthy of note, including the wereraven, the weresnake, the werecrocodile, and the dreaded wereshark.

   1999, Van Richten's Monster Hunter's Compendium, volume 1, Renton, WA: Wizards of the Coast, →ISBN, page 123

   2 more examples

   But even warrior-priests as mighty as those of the Silver Flame have their limits, and while the Purified carried out their Purge on land, they were unable to do anything about the lycanthropes that inhabit the seas. The creature that attacked you was a wereshark, Haaken.

   2008, Tim Waggoner, Sea of Death (Blade of the Flame), Renton, WA: Wizards of the Coast, →ISBN, page 105

   Weresharks are human except when they come in contact with salt water, at which time they transform into horrifying, bloodthirsty creatures with shark heads, gills, and dorsal fins, but human bodies.

   2019, George Brewington, The Monster Catchers: A Bailey Buckleby Story, New York, NY: Henry Holt and Company, →ISBN, page 126