Bella Goth is a pre-made deceased Sim from The Sims 3, her tombstone is located in the graveyard of Lunar Lakes. She follows the standard of appearance as seen in most of Lunar Lakes' deceased Sims. SimGuruSarah has confirmed that she is the same Bella as the one that appeared in Pleasantview and Sunset Valley. How and why she ended up in Lunar Lakes is left unexplained. There is a possibility she is the ancestor of the mail woman, Mathilde Goth, from the same town.
This version of Bella also has completely different personality traits to the Bella in Sunset Valley, but it could be assumed that her personality was biologically altered when she was abducted by aliens.