Lilyroo

A Lilyroo (a portmanteau of a kangaroo and Lily Loud) is a non-sapient mammal that resembles Lily Loud in a kangaroo costume that she wears in a Loud House episode, Tricked!, to real life Earth.

 They are all in the age of 15 months, like Lisa Loud in that show, where she is at the age of 15 months, and they don't age at all, so they keep themselves 100% 15-month olds, because they are generated by a team of Australian common human scientists.

Unlike in the music video sung by Luna Loud that promotes that epsiode, Tricked!, where Lilyroo looked scary and aggressive, Lilyroos are very peaceful to all sapient species and beings, except vampires, due to bloody conflicts with them, plus they are rather docile, calm, and peaceful, unless if there are predators and vampires that are bound to harm them.

Like that music video, and the picture, they can also have rabies, but only for self-defense purposes as well, because using rabies for no reason, like in the music video, is not very tolerated to humans as well.

They are herbivores, and they can eat grasses, flowers, leaves, ferns, mosses, and even insects.

They are mainly found in forests, and even in human settlements.

Unlike in movies, they were never humans, as humans are primates that are part of the ape family, while Lilyroos aren't primates at all.