Nell Williams is an English actress. In season 5 of the HBO series Game of Thrones she will portray a younger version of Cersei Lannister (p…Nell Williams is an English actress. In season 5 of the HBO series Game of Thrones she will portray a younger version of Cersei Lannister (portrayed by Lena Headey as an adult) in flashback sequences.She has also appeared in The Revolting World of Stanley Brown and Loving Miss Hatto