Cephalopod

Throughout the universe, various cephalopodic species exist. This is one of the many shapes that recur throughout the universe, including insectoid and humanoid.

In the 51st century, cephalopods (or at least cephalopod-humanoids) may interbreed with humans. Ianto Jones expressed of his boyfriend, Jack Harknes, fear of a boyfriend leaving him equally for "men, women, or cephalopods" (TWN: The House that Jack Built).