Charlie Rhodes
Charlie Rhodes is the cousin and half sister of Serena and Eric Van Der Woodsen. She is the daughter of Carol Rhodes (Lily's sister) and WIlliam Van Der Woodsen. In season 4 she is revealed as Serena's cousin, but her mother Carol Rhodes, hired an actress - (Ivy Dickens) to play Charlie Rhodes as Serena's family. When Carol is exposed for hiring an actress to play her own daughter, she is shunned out of the family.