Millie is a rather large woman who tends to tower over other people. Her intimidation factor is not helped by the muscles developed due to her work as a butcher, along with the strength imparted to her from other sources. She has fair skin, only interrupted by many small scars along her forearms (usually covered by her clothes) and much larger scars on her abdomin. The scars on her arms are usually from small scrapes and burns, while on her stomach they come from much larger lacerations. On most of her body (but particularly around her shoulders, abdomin, and back) are metal and circuitry from augmentations that weren't able to be fully removed without damaging her muscles or organs. From the middle of her forearm down to her hands is replaced by mechanical claws. She has dark brown eyes and fluffy blonde hair, usually held up in a bun aside from some parts in the front. The front of her hair flops over in a way that looks comparable to dog ears.

To try and cancel out the intimidation factor from her stature, Millie dresses in a very cutesy and nonthreatening manor. She enjoys wearing t-shirts with cute graphics along with clothes too big for her, in attempt to make herself look smaller. She wears pants more often than skirts or dresses, and usually is wearing a pair of white sneakers. Millie's favorite article of clothing is a pink sweather that's a bit too large for her, which she wears off the shoulders with the sleeves very far over her hands. She'll often try to do normal activities with her sleeves over her hands, such as signing reciepts or trying to do hand gestures. A pink scrunchie usually holds her bun in place (over a ponytail holder).