Wilhelmina Leaf is a pre-made deceased Sim who once lived in Twinbrook. She died as a child and is now buried in Ivy Hill Graveyard. She died from electrocution and she has a medium-sized gravestone, indicating she has earned a medium amount of lifetime happiness points. She is one of the six pre-made deceased children in The Sims 3 series. The others are Opal Suarley from Sunset Valley whodrowned, Kirsten Remington from Riverview who drowned, Marabel Goldbeard from Barnacle Bay who drowned, Davey Moans who was also from Barnacle Bay who was burnt to death, and Sandra Salas from Midnight Hollow who was electrocuted.
Technically, it's not possible for children to die from electrocution. This is probably an oversight by the developers. How Wilhelmina really died from electrocution is up to the player's imagination. She and Sandra Salas both died from electrocution. However, Sandra was likely born a Ghost baby and her parents both died of electrocution.
She has pale green skin, grey hair and is barefoot like all the other deceased Sims of Twinbrook.