Léa Hélène Seydoux-Fornier de Clausonne (French: [le.a sɛ.du] (listen); born 1 July 1985) is a French actor. Known for her roles in both French cinema and in Hollywood she has received various accolades including five César Award nominations, the Cannes Film Festival's Trophée Chopard in 2009, as well as a nomination for the

BAFTA Rising Star Award in 2014. In 2016, Seydoux was honoured with the Chevalier of the Order of Arts and Letters. In 2022, the French government made her an Officer of the Legion of Honour.

She began her acting career with her film debut in Girlfriends (2006) with early roles in The Last Mistress (2007) and On War (2008). She won acclaim for her French roles in The Beautiful Person (2008), Belle Épine (2010), and Farewell, My Queen (2012). During this time she expanded her career appearing in minor roles in high-profile Hollywood films, including Quentin Tarantino's Inglourious Basterds (2009), Ridley Scott's Robin Hood (2010), Woody Allen's Midnight in Paris (2011) and the action film Mission: Impossible – Ghost Protocol (2011).

Her breakthrough role came with the controversial and acclaimed film Blue Is the Warmest Colour (2013) for which she received the Palme d'Or at the Cannes Film Festival along with her co-star Adèle Exarchopoulos. She received the Lumières Award for Best Actress for the film Grand Central (2014). She gained international attention for her role as Bond girl Madeleine Swann in Spectre (2015), and No Time to Die (2021).She has appeared in the Wes Anderson films The Grand Budapest Hotel (2014) and The French Dispatch (2021). Other notable roles include Beauty and the Beast (2014), Saint Laurent (2014). The Lobster (2015), France (2021), Crimes of the Future (2022), and One Fine Morning (2022).

Seydoux is also known for her work as a model. She has been showcased in Vogue Paris, American Vogue, L'Officiel, Another Magazine and W magazine among others. Since 2016, she has been a brand ambassador for Louis Vuitton.