Mullo

 is a kwami that is connected to the Rat Miraculous. With their power, its wearer can use the Miraculous to transform into a rat-themed superhero. They are currently dormant in their Miraculous in Wang Fu's Miracle Box, as seen in "Sapotis".

Appearance
Mullo is light gray with a small body, two whiskers, and a thin tail. They have pink eyes and gray ears with the insides being pink.

Abilities
Mullo can fly, levitate, and phase through solid objects. They can also carry objects that are larger and/or heavier than them.

As a kwami, Mullo is able to transform the holder of the Rat Miraculous into a rat-themed superhero, although it is unknown what the transformation looks like or what powers the transformed person gains.

Before Season 2
Before the Miraculous jewels were created, Mullo and the other kwamis traveled all over the universe unable to interact with humans. Thousands of years ago, a mage created the Miraculouses. When their Miraculous was not being worn, Mullo was dormant in the Rat Miraculous, which was stored inside the Miracle Box.

Season 2
During Season 2, Mullo was dormant in the Rat Miraculous.

Trivia

 * Mullo was first revealed from a second season trailer on August 31, 2017.
 * Thomas Astruc revealed their name on Twitter on November 11, 2018.
 * Rats are symbols for many things, including success, ambition, kindness, and resourcefulness.
 * The rat is the first animal of the Chinese zodiac.
 * Mullo's name is a reference to "mulot", a French word for "field mouse".

Concept art
Kwami ratón Kwami Rat pt-br:Kwami do Rato