Mary Joestar

Mary Joestar (メアリー・ジョースター Mearī Jōsutā) is the late mother of Jonathan Joestar and wife of George Joestar I. She is never shown in person in the series, the only thing known about her backstory is that she accompanied her husband during a trip to London and died protecting her baby when her carriage had an accident and fell off a cliff.

History
It is shown that Mary died in the fateful cart accident that Dario Brando "saves" her husband George Joestar I from. Mary's face is later seen in a picture in Jonathan's room. The night Danny dies, Jonathan is seen crying and looking at the picture, missing his mother. Years later, Jonathan studies the mechanics behind the stone mask, mentioning how the mask was originally obtained from his mother's travels.

When Dio Brando is revealed to have been poisoning George, a police inspector tells Speedwagon that Dario stole her wedding ring from her corpse and tried to sell it. George knew the truth but willingly gave the ring back to Dario after he was detained in prison and told him to sell it, hoping Dario would turn his life around for the better.