Executive for Vanger Corporation
Cecilia Vanger is a member of the Vanger family.
She's the headmistress of Hedestad primary school. Her father is Harald Vanger (the only living brother alongside Henrik Vanger), a Nazi who "ruined [her] life when [she] was just a child". He's called her a "whore" since she was 21 when he found out she lost her virginity to a man with Jewish ancestry. The two never speak to each other.
Encounter with Mikael
In The Girl with the Dragon Tattoo she has a fling with Mikael Blomkvist that turns into an affair. The affair ended when he have to be imprisoned unexpectedly, leaving her devastated. She realized that she had feelings for him, and would not continue to speak to him. In the Swedish film version of The Girl With the Dragon Tattoo the affair is left out entirely. In the American adapation, Cecilia appears as an enemy of Mikael instead.