Premise: A Song of Ice and Fire is a series of epic fantasy novels by the American novelist and screenwriter George R. R. Martin . Cersei Lannister is a fictional character in the A Song of Ice and Fire series of fantasy novels by American author George R. R. Martin , and its television adaptation Game of Thrones , where she is portrayed by Lena Headey .
Hypothesis: Cersei Lannister is in a book series.
Label: ENTAILMENT