Grandma Spankenheimer is one of the main characters from the Christmas special, Grandma Got Run Over by a Reindeer. She is Grandpa's wife, Frank's mother, Rita's mother-in-law and Jake, Daphne and Mel's grandmother.
She and her family runs a store in Cityville and does not wish to sell it to Austin Bucks, who owns the other properties in town, much to the annoyance of her gold digging granddaughter Mel.
One Christmas Eve, Grandma goes outside with her famous fruitcake (which had been spiked by Mel) and is run over by Santa Claus' sleigh. Jake witnesses it, but is unable to convince his family. The next morning, Grandma is missing, where in fact she had been taken back to The North Pole by Santa to be healed.
The following September, Jake contacts Santa and is brought to the North Pole by Santa's head elf Quincy. Jake reunites with Grandma, but is shocked to discover that she has amnesia and does not remember him. In an effort to try and restore her memory, Jake and Santa take Grandma back to Cityville.
However upon returning to Cityville and left alone in the sleigh, Grandma is lured away by Mel and her attorney I.M. Slime, who keep her in a cabin and accuse Santa of kidnapping her. Three months later, Jake and Quincy find and rescue Grandma and discover a note Santa had left to explain Grandma's whereabouts (which Mel had hidden from the rest of the family) and a vial of the ingredient Mel used to spike Grandma's fruitcake, which attracted Santa's reindeer and caused Grandma to be run over. Jake and Quincy are able to restore Grandma's memory by feeding her fruitcake. After Jake explains to Grandma what has happened, they head off to the courthouse where Santa is on trial.
They arrive at the courthouse and reveal the truth about Mel. After Mel is jailed, Austin Bucks tells Grandma that he wishes to franchise her store throughout the country. Afterwards, Grandma accidentally takes the spiked fruitcake away with her again and once again gets run over by the sleigh, but luckily is alright and doesn't get amnesia.