Hexabby

At a glance, Abby usually appears to be a 6-year-old human girl with curly ginger hair, but the reality is far from that appearance.
Abby is a timeless shapeshifter from outside all universes.
Her true form is unknown even to her, as her shapeshifting is subonscious and has been happening ever since she spawned.
Despite her age and accumulated experiences, Abby is maladjusted to the social norms of cultures.
Because of this, Abby takes a childish form; it comforts her and seems to make social interactions less hostile.

Abby is a hedonist. She enters universes to experience all the pleasures there are to explore--food, sex, romance, pain--if she thinks she'll like it, she wants to try it.

Abby's corporeal body reforms constantly, making her immune to injury but still feeling the sting.
She can choose to make her body vulnerable to harm though, allowing it to be injured or digested.
When Abby feels trapped or cornered, she's been known to shift realities, vanishing from one place entirely and appearing in another.
She can also open rifts to other universes, including her "home".
Her usual height is 2'9".

Given the nature of Abby's body, she is able to mimic another creature's genome upon touching them directly.
This allows her to either turn into a clone of whomever she's touching or transform into a member of the species.
Unfortunately, this doesn't grant her any magical abilities that species may have, as Abby is not magical. She's limited to whatever she can accomplish with her body.
However, it does mean there are many species or 'forms' Abby can transform into at will.
These are the ones she's picked up on her travels so far:
Human. Abby has lots of experience with the human genome and can alter her body in strange, body horrific ways when in this form.
Indominus Rex
Dog
Pikachu
Mew
Vulpix
Rockruff
Demon-Fox hybrid
Catgirl
Grass. (Yes, she's touched it)
Dragon
Orc
Goblin
Sentient panties
Sentient sundress
Incubus