Isabella was a one-shot villainess from Supernatural, appearing in Season Ten's "Paint it Black."
She was played by Catherine Michaud.
In 1520, Isabella was a young Italian woman who met and fell in love with an artist named Piero, who wanted to paint portraits of her. She was so enamored by Piero that she even used her own blood in the portraits, but her love was never reciprocated, as Piero stated that he was only in love with his work. Isabella was forced to join a convent, only taking her journal with her, but she eventually snuck out and got her revenge on Piero by killing him after she caught him with another woman. Isabella was burned at the stake and accused of witchcraft for her crime.
In the aforementioned episode, Isabella resurfaced in a church in Worcester, Massachusetts, where her journal and her portraits were. She became an evil, vengeful spirit and killed men who had been unfaithful to their women, doing so by possessing the victimized women. Isabella formed a friendship with Sister Mathias, who she told about her relationship with Piero (of course, leaving the gory details out). After Mathias learned the truth about Isabella, she contacted Sam and Dean, who later searched for Isabella, only to find that she had killed a priest; doing so because she was upset over him forgiving people for their sins. After killing the priest, the evil Isabella possessed Mathias and attempted to kill Dean, who called for Sam to burn her journal. Sam actually learned that the paintings were the real connection and burned them, which ejected Isabella from Mathias' body. Isabella screamed for Mathias to help her, but Mathias refused and Isabella was burned away for good.