Rebecca Goth is a non-playable Sim shipped with the game in Sugar Maple Coast, a neighborhood in The Sims 3 Pets (console). She lives with her cat, Buttons Goth. Her relationship, if any, to the Goth family is unknown.
Rebecca Goth was drawn to Sugar Maple Coast due to the stories of her family there. This suggests that she could be a distant relative of the late Timaeus Goth. She can be made playable by asking her to move in.