Lena Kathren Headey (born 3 October 1973) is a British actress. She gained international recognition and acclaim for her portrayal of Cersei Lannister on the HBO epic fantasy drama series Game of Thrones (2011–2019), for which she received five Primetime Emmy Award nominations and a Golden Globe Award nomination.

Headey made her film debut in the mystery drama Waterland (1992). She continued to work steadily in British and American films and on television, before gaining further recognition with her lead performances in the films The Brothers Grimm (2005) and 300 (2007). Her other film credits include The Remains of the Day (1993), The Jungle Book (1994), Mrs Dalloway (1997), Ripley's Game (2002), Imagine Me & You (2005), Dredd (2012), The Purge (2013), 300: Rise of an Empire (2014), Pride and Prejudice and Zombies (2016), and Fighting with My Family (2019).

Outside of film, Headey starred as Sarah Connor in the science fiction television series Terminator: The Sarah Connor Chronicles (2008–2009) and had a recurring role as Amelia Hughes in the animated web series Infinity Train (2019–2021). She provided voices for the role-playing video game Risen (2009) and the video game tie-in film Kingsglaive: Final Fantasy XV (2016), as well as the animated series Danger Mouse (2015–2017) and Trollhunters (2017–2018), and puppet-animated series The Dark Crystal: Age of Resistance (2019).