William James Remar (born December 31, 1953) is an American actor. Some of his best known film roles are as Ajax in The Warriors (1979), as homicidal maniac Albert Ganz in 48 Hrs. (1982), as Dutch Schultz in The Cotton Club (1984), and as Lord Raiden in Mortal Kombat: Annihilation (1997). He has had smaller roles in many other notable films, including Drugstore Cowboy (1989), Boys on the Side (1995), Judge Dredd (1995), Psycho (1998), What Lies Beneath (2000), 2 Fast 2 Furious (2002), Blade: Trinity (2004), Ratatouille (2007), Pineapple Express (2008), RED (2010), X-Men: First Class (2011), Django Unchained (2012), Once Upon a Time in Hollywood (2019), Oppenheimer (2023), and Megalopolis (2024). He was originally cast as Corporal Hicks in Aliens (1986) before being replaced by Michael Biehn.

On television, Remar's recurring roles include Richard Wright, the on-off tycoon boyfriend of Samantha in Sex and the City (2001 - 2004), Harry Morgan in Dexter (2006 - 2013) and Dexter: Resurrection (2025 - present), the voice of Vilgax in Ben 10 (2009 - 2012), Tonraq in The Legend of Korra (2013 - 2014), and Peter Gambi in Black Lightning (2018 - 2021). He also voices Executor Hideo in the Destiny video game series.

Remar has been married to Atsuko Remar since 1984. They have two children.