She is the vengeful spirit of a dead animator who previously worked on a Sonic the Hedgehog cartoon alongside her husband, Thomas. Following his murder, alongside the deaths of her kids, Lilith would spiral into depression before eventually passing away under unknown circumstances. However, Lilith's soul was angry and filled with hate, and she returned as a ghost possessing the old cartoon she previously worked on, dedicating her new undead life towards killing the people who wronged her, including that of her fiancé's killer, and reuniting with him.

The Ghost Girl, also known as the School Girl, is a minor character of the Slendytubbies series. The Ghost Girl is stated to be Laa-Laa's imaginary friend