Mya Peterson is the daughter of Theodore Peterson and Diane Peterson, and the younger sister of Aaron Peterson. She is the only playable character in Hello Neighbor: Hide and Seek. Mya dies when Aaron pushes her off the roof at the end of the game.
Mya is a ten year old girl. Her eyes are blue and her red hair is gathered in pigtails. Her eyebrows are small, unlike her brother. Additionally, she has a small nose and freckles. Dressed in a striped blue and white short-sleeved shirt and turquoise dress with small suspenders on top. There is a bracelet on her right hand. On her feet, she wears sandals with orange bows. This appearance is also used in Stage 5.
This is a piece of cardboard on which the outline of a child-girl is drawn. On the cardboard, you can see pigtails, white eyes,and a nose. On the painted child, you can see a dress with small suspenders.
Mya's clothes have changed a bit. Mya is now wearing an ocher short-sleeved shirt. She has a special explorer hat. She is wearing pale beige shorts. Now, instead of a bracelet, she has a wristwatch. Instead of sandals, she has brown boots.
She looks like an ordinary thief. She is wearing black gloves and a mask. She also wears a black and white shirt with long sleeves. She is wearing dark gray pants and a hat. He also wears dark gray boots.
Dressed as a firefighter. She is dressed in special firefighter clothes in red with yellow accents. She has a special fire helmet. She also has a black belt with a gold buckle. Now she has brown shoes.
Mya looks almost the same as usual, but the clothes look more disheveled and pale. She has pale green tattered skin. Hair and eyebrows have a paler shade. On her right foot, the sandal has become more disheveled, and on the left foot is completely absent.
Hello Neighbor- December 8, 2017
Hello Neighbor: Missing Pieces- August 28, 2018
Hello Neighbor: Hide and Seek- December 6, 2018
Hello Neighbor: Waking Nightmare- December 26, 2018
Hello Neighbor: Buried Secrets- July 30, 2019
Hello Neighbor: Bad Blood- December 26, 2019
Hello Neighbor: Grave Mistakes- August 4, 2020
Mya, much like Mr. Peterson, has light skin and green eyes. Though unlike her father, she has light-colored hair like her mother's. She also has a bird tattoo on the inside of her wrist. Mya died when her brother pushed her off the roof at the end of stage 5 in Hello Neighbor: Hide and Seek.
Hello Neighbor: Hide & Seek: Playing hide and seek with her brother while their mom is preparing breakfast. Then the parents leave, and the children continue their game. However, only her father comes home; he falls to the floor in tears and her mother’s bag in her hands. The mother of the children died. If Mya suffered this pain, then Aaron did not. While playing hide and seek, her brother Aaron accidentally threw her off the roof. Mya did not survive the fall.
Act 1: Her shoes are in Mr. Peterson's House at the entrance. You can also see a dream in which the Neighbor buried her with the shovel.
Act 2: Her coffin is buried in the backyard of Mr. Peterson. In the coffin is only the key to the dollhouse, which represents Mya. Also, her shoes are in Mr. Peterson's House in the entrance. You can also find a roller coaster dream where it is on the roof.
Act 3: She can be seen in a photograph of her neighbor’s family in the family room, as well as her shoes.
Story excerpts featuring Mya are shown in the dreams of Nicky Roth.
Mya is a kind girl, as shown when she tried to cheer Aaron up after their mother died. She has a wide imagination and likes playing. Mya has a doll which she really loves to play with.
- She is voiced by Varvara Pronina 
- She is referred to as Sister in the credits of Hello Neighbor: Hide and Seek.
- Initially, this was not a confirmed character, but in the Full Game, the developers confirmed its presence in the game.
- The girl herself has never met in the Hello Neighbor, only in Hello Neighbor: Hide and Seek. It can be seen only in the form of a model drawn on cardboard, or in a family portrait.
- In the game, you can find some things that belong to the girl (dollhouse, shoes, and others).
- For the first time, she appeared in Secret Neighbor’s first trailer, “Hello Neighbor Battlegrounds Announce Teaser,” running to Nicky's company.
- Diane Peterson refers to her as "Mouse"