Cersei Lannister is in a series by George R. R. Martin.
A Storm of Swords is the third of seven planned novels in A Song of Ice and Fire , a fantasy series by American author 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 .