Lena was born in Bermuda, where her father, a police officer was stationed. The family moved to Huddersfield, Yorkshire when Lena was five years and remained their until Lena was seventeen. At the age of seventeen Lena was spotted by a Hollywood casting agent during her performance in an one-off show and her acting career began.
In 1992, Lena made her big screen debut in the film Waterland. Over the next thirteen years Lena landed major and minor roles in numerous films, TV movies and television series. Lena enjoy acting and being able to live a somewhat normal life.
In 2006, Lena landed the role of Queen Gorgo in the blockbuster hit 300 elevating her fame level.
In the fall of 2009 Lena was cast as Cersei Lannister in the HBO series Game of Thrones. She has played the part since the show's debut in the Spring of 2011. In the summer of 2012 Lena was cast as Jocelyn Fray in The Mortal Instruments film series.
As of 2014, Lena resides in Sherman Oaks, California with her son, Wylie and their numerous pets.