Mary is the late wife of George Joestar and mother of Jonathan Joestar. She accompanies her husband during a trip to London and dies protecting her baby when the carriage has an accident and falls off a cliff.
Mary has short curly light hair kept up to her neck. She wears a choker necklace with a locket along with a Victorian dress. Her dress is decorated with a rose.
At some point in the 1860s, Mary and George Joestar have a pair of rings made by a famous jeweler for their engagement. They later have a son named Jonathan Joestar on April 4, 1868. Shortly after Jonathan's birth, Mary and George travel with him to an art gallery in London. George finds a Stone Mask there and takes a liking to it, and Mary buys it for him.
On their way home, their carriage slips off a cliff in the rain; Mary dies in the accident while protecting her baby. Dario Brando sees their bodies and, assuming no one in the carriage survived, steals the wedding ring that Mary gave George. However, George awakens and misinterprets Dario's actions, believing that he had saved him and the baby. When Dario confirms Mary's death, George laments that he should have died instead of her, though he is thankful their son is safe.
George keeps the Stone Mask hung on one of the walls of the Joestar Mansion as a memento of Mary. Jonathan also keeps a photo of Mary on top of his bed's headboard. After being isolated by Dio, Jonathan looks at the photo and cries, missing her despite having no memory of her.
Seven years after Dio's adoption, Jonathan studies the Stone Mask, mentioning how the mask was originally obtained from his mother's travels. He feels a sense of longing to see her despite having no memories of her.