Emily Margaret Watson (born 14 January 1967) is an English actress. She began her career on stage and joined the Royal Shakespeare Company in 1992. In 2002, she starred in productions of Twelfth Night and Uncle Vanya at the Donmar Warehouse. She was nominated for the Olivier Award for Best Actress for the latter. She was nominated for the Academy Award for Best Actress for her debut film role as a newlywed in Lars von Trier's Breaking the Waves (1996) and for her portrayal of Jacqueline du Pré in Anand Tucker's Hilary and Jackie (1998).

Watson's other films include The Boxer (1997), Angela's Ashes (1999), Gosford Park (2001),  Punch-Drunk Love (2002), Red Dragon (2002), The Life and Death of Peter Sellers (2004), Corpse Bride (2005), Miss Potter (2006), Synecdoche, New York (2008), Oranges and Sunshine (2010), War Horse (2011), The Theory of Everything (2014), Kingsman: The Golden Circle (2017), God's Creatures (2022), and Small Things like These (2024). 

She was nominated for a Primetime Emmy Award and a Golden Globe Award for her role in the HBO miniseries Chernobyl. She won the British Academy Television Award for Best Actress for playing Janet Leach in the 2011 ITV television biopic Appropriate Adult. She was nominated for the International Emmy Award for Best Actress for the 2017 BBC miniseries Apple Tree Yard. In 2024, she portrayed the lead role of Valya Harkonnen in the HBO science fiction series Dune: Prophecy.

Watson is a supporter of the children's charity the NSPCC. In 2004, she was inducted into the society's hall of fame for spearheading the successful campaign to appoint a Children's Commissioner for England. Receiving her award in the crowded House of Commons, she spoke out against the possibility that the Children's Commissioner become a figurehead with little real power.