Gregory Mama is an old mouse sorceress residing within Gregory House and the mother of Gregory as well as great grandmother of James. She is a major antagonist of Gregory Horror Show and the final boss of Gregory Horror Show: Soul Collector.
During the second series The Second Guest, she is revealed to be collecting lost souls that wander to Gregory House so she can consume them in an attempt to keep herself "beautiful". She is seemingly destroyed when Neko Zombie burns down Gregory House but resurrects along with Gregory and James. The Second Guest then becomes part of their family.
She appears in the third series The Last Train where she is impersonated by a con artist telephone to trick Gregory into giving more and more money to it. Not flattered by the imitation, she destroyed the phone.
Her role in the game is similar to The Second Guest where she becomes angered over the player character's success in getting the souls from the residents. She appears in the final part of the game and knocks the player character unconsious. The player character comes to and moves to escape to the real world, but the gateway (i.e. the front doors of Gregory House) are locked. Enraged, Gregory Mama attacks the player character with blasts of energy. The player character tricks her into destroying the doors so he/she can escape to the real world.
Ultimately, Neko Zombie burns down the house but the player character returns to become a permanent resident of Gregory House. It is presumed that Gregory Mama was resurrected as Gregory had.
Gregory Mama is extremely vindictive and quick to fly into a rage when things do not go according to plan. She frequently subjects Gregory to physical abuse, usually rapping him on the skull with her staff, when he fails her. She is also incredibly vain, believing herself to be beautiful. This is what prompts her collection of the various souls to consume so that she may be revitalized. She also shows signs of being as much of a pervert as her son. In the aforementioned Last Train episode, she had posters advertising herself as a phone sex operator.
Despite these traits, she shows some familial traits. At the end of The Second Guest, she offers the eponymous second guest a chance to become part of their family. In one episode of The Bloody Karte, she becomes incredibly angry with the idea of James reading a dirty magazine at his age...and by extent Gregory owning one.