She has voluminous white hair pulled back into a poofy pixie cut-like shape, which ends in multiple backwards spikes. She has a wrinkly face with a pointed chin, and a wide, short, upturned nose. Her left eye is missing. At first glance, she appears very tall, with Morticia only reaching up to around her chin. However, the majority of her dress is not a part of her body, but rather a height enhancement device. Her legs are incredibly short and she is shorter than Grandmama. She wears a mid pale green dress with a spiked collar and dark green elbow-length gloves.
Sloom showed up at the Addams house to oversee Pugsley's Mazurka. As Pugsley struggles with his Mazurka passage, Sloom is present when Margaux Needler leads an angry mob from Assimilation into attacking the house and is among those evacuated by Wednesday and Ichabod.
After the people of Assimilation have made peace with the entire Addams Family and Uncle Fester has come up with a compromise with Margaux, the Mazurka resumes, with Sloom declaring that Pugsley passed after seeing how he helped to defend the house.
She is strict and cold, especially towards her younger family members.
She was voiced by Jenifer Lewis.