Stellan Skarsgård (, Swedish: [ˈstɛ̂lːan ˈskɑ̌ːʂɡoːɖ] (listen); born 13 June 1951) is a Swedish actor. He is known for his collaborations with director Lars von Trier appearing in Breaking the Waves (1996), Dancer in the Dark (2000), Dogville (2007), Melancholia (2011), and Nymphomaniac (2014). Skarsgård's early English-speaking film roles include The Unbearable Lightness of Being (1988), The Hunt for Red October (1990), Good Will Hunting (1997), Ronin (1998), and King Arthur (2004).

Skarsgård has since starred in various blockbusters such as Pirates of the Caribbean: Dead Man's Chest (2006) and Pirates of the Caribbean: At World's End (2007). He also starred in Mamma Mia! (2008), Angels and Demons (2009), David Fincher's thriller The Girl With the Dragon Tattoo (2011) and Dune (2021). Since 2011 he has appeared in the Marvel Cinematic Universe, portraying Dr. Erik Selvig in Thor (2011), The Avengers (2012), Thor: The Dark World (2013), Avengers: Age of Ultron (2015), and Thor: Love and Thunder (2022).

He is also known for his work in television portraying Boris Shcherbina in the HBO miniseries Chernobyl (2019) for which he received the Golden Globe Award for Best Supporting Actor – Series, Miniseries or Television Film and a nomination for the Primetime Emmy Award for Outstanding Supporting Actor in a Limited or Anthology Series or Movie. He stars in the Star Wars prequel series Andor (2022) on Disney+.