What is a creature that half man octopus called?

There isn't a specific name for a creature that is half-man, half-octopus. That kind of creature is purely fictional and exists only in fantasy, mythology, or science fiction.

Here are some possible ways to refer to such a creature:

* Merman/Merwoman with tentacles: This emphasizes the human-like aspects and adds the octopus feature.

* Octo-humanoid: This emphasizes the octopus-like aspects and highlights the humanoid form.

* Cephalopod Man: This is more generic but accurately reflects the creature's origins.

Ultimately, the best name will depend on the specific context and the creature's role in the story.