AMM is the sole inhabitant of The Void. AMM's "natural" form is essentially gibberish, but they have created a humanoid form to prevent confusion. AMM created the Strawberry Mug, for reasons currently unknown- though it could be inferred that it was created out of boredom.
AMM made their first appearance in the Episode "Introduction".
A few 009; fans have taken to referring to AMM as "lmao". This was most likely inspired by the first line of dialogue in the Episode "Blue Hour".