[Icelander]

Originally Posted by Pip Boy

Yes, there are some, but not so much in a horrific way, but as a lore of the land, creatures of folklore. Perhaps you can use them with a twist.

There is the boto cor de rosa (Pink Boto) (https://pt.wikipedia.org/wiki/Lenda_do_boto), a river dolphin that impregnates women. The tale it's not from Rio, however, but from the North region of Brazil.

There is the Iara, a kind of mermaid (https://www.infoescola.com/folclore/iara/), that bewitches men to drown them.

Here its a list of some folklore creatures:
https://pt.wikipedia.org/wiki/Folclore_brasileiro

Great, thanks!

What would be good names for humanoids that come from beneath the sea, look human, but are not? Ichthyoid, batrachian infiltrators in the style of Lovecraft's Deep Ones, enchanted beings of superhuman ability with no respect for human mores, feelings or lives. They are often powerful sorcerers and have alien, inscrutable goals.