New Earth
Sheila Haywood was a doctor in Gotham City who fell in love with Willis Todd, leading to the birth of their son, Jason Todd. However, Sheila had to leave the city shortly after Jason’s birth, and Jason was instead raised by his stepmother, Catherine Todd.
Years later, Jason (now the second Robin and partner of Batman) discovered that Catherine was not his biological mother after finding his birth certificate, where the name of his mother was illegible except for the letter S. After several false leads, Robin and Batman tracked down Sheila, who was working at an aid camp in Ethiopia; she confirmed that she was Jason’s biological mother, and the two reunited.
Shortly after, however, Sheila was confronted by the Joker, who blackmailed her with evidence of her embezzling from the aid organization she worked for. Sheila lured Jason into a warehouse, promising him that Joker had left, and instead delivered him into Joker’s hands, watching impassively as Joker brutally beat Jason with a crowbar. Joker then turned on Sheila as well, leaving her tied up in the warehouse alongside Jason with a bomb ticking down.
Despite her betrayal, a badly wounded Jason untied Sheila in an attempt to save her. Sheila tried to help Jason out of the warehouse, only to discover that the door was barred; the bomb then exploded, destroying the warehouse and killing Jason. Batman arrived to find Sheila barely alive; she told Batman that Jason had tried to protect her from the blast before dying from her injuries.
New 52
Sheila does not appear in the New 52; instead, Catherine Todd is Jason’s biological mother, and is used by Joker to lure Jason to his death.