Mrs. Garrison Senior is Mr. Garrison's mother from Arkansas. She first appeared in the Season Three episode "World Wide Recorder Concert", and made a cameo appearance in the Season Twenty episode, "Oh, Jeez".
In "World Wide Recorder Concert", Herbert Garrison is in town visiting, and confronting some unfinished demons he has with his father. Garrison believes that his father didn't love him, because he never sexually abused him. His mother insists that wasn't the case, and tries to support her son. In the end, Mr. Garrison Senior and Mr. Garrison reconciled, much to the joy of Mrs. Garrison.
Mrs. Garrison is an elderly lady with shoulder-length, wavy, and receding hair that is the same steel gray as her son's. She wears a white, long-sleeved shirt with gold buttons and a baggy, purple cardigan with a v-neck. She tucks this into her dark blue skirt, which covers her knees. She wears white tights, pink lipstick, and small black-framed rectangular glasses.
Mrs. Garrison is much more like her son, and it is possible that he got his warped perspective on life from her because she was his primary carer. She becomes hugely upset when Mr. Garrison says that his father never sexually molested him as a child, denying she knew this, crying "If I knew, I would have made him do it!" through tears.
She also says that her husband "did the right thing" when she thought he'd had sex with Mr. Garrison at night. She is very close to her son, repeatedly stating how proud she is that he's involved in the World Wide Recorder Concert. In turn, he seems very close to her; after he reduces her to tears by accusing her of being complicit in his father's non-abuse, he runs after her saying he's sorry. She thinks sexual molestation is an act of love, and insisting her husband molested Mr. Garrison "repeatedly", as if it was his duty as a father.
- "Damien" (mentioned) - Mr. Garrison mentions that his mother was from Alabama after Damien Thorn says he's from the seventh layer of Hell.
- "World Wide Recorder Concert" - Seen consoling her son about the lack of sexual abuse by his father.
- "Go God Go XII" - Cameo; seen in a photograph.
- "Oh, Jeez" - Cameo; seen in a photograph.