Mrs. Spencer is an old lady and neighbor of the Smith Family. She is often seen walking her cat around the neighborhood.
Mrs. Spencer was recreated in the Zigerion scammers' simulation of Earth. Rick Sanchez, after pulling Morty Smith out of school and undressing to walk around naked, pointed her out as an example of design flaws with the simulation because she was walking her cat on a leash. Morty, however, claimed that she walk her cat all the time, before Rick went on to wackier examples.
The Mrs. Spencer of dimension C-500A was in the crowd of people outside of Jerry Smith (C-500A)'s release party for his newest movie, "Last Will and Testimeow: Weekend at Dead Cat Lady's House II". When Jerry suffered a nervous breakdown and exited the party, he assaulted Mrs. Spencer and stole her mobility scooter, which he "payed" for by throwing coins at her (which turned out to be worthless R2D2 collectible coins), while screaming "I HAVE TO FIND HER".