Joseph Hill Whedon (; born June 23, 1964) is an American screenwriter, director, producer and comic book writer. He is the founder of Mutant Enemy Productions, co-founder of Bellwether Pictures, and is best known as the creator of several television series: the supernatural drama Buffy the Vampire Slayer (1997–2003) and its spinoff Angel (1999–2004), the short-lived space Western Firefly (2002), the Internet musical miniseries Dr. Horrible's Sing-Along Blog (2008), the science fiction drama Dollhouse (2009–2010), the Marvel Cinematic Universe series Agents of S.H.I.E.L.D. (2013–2020), and the science fiction drama The Nevers (2021).

After beginning his career in sitcoms, Whedon wrote the poorly received horror comedy film Buffy the Vampire Slayer (1992) – which he later adapted into the acclaimed television series of the same name – co-wrote the Pixar animated film Toy Story (1995), and wrote the science fiction horror film Alien Resurrection (1997). After achieving success as a television showrunner, Whedon returned to film to write and direct the Firefly film continuation Serenity (2005), co-write and produce the horror comedy film The Cabin in the Woods (2012), and write and direct the Shakespeare adaptation Much Ado About Nothing (2012). For the Marvel Cinematic Universe, Whedon wrote and directed the ensemble superhero film The Avengers (2012) and its sequel Avengers: Age of Ultron (2015). He also co-wrote the DC Extended Universe superhero film Justice League (2017), for which he also served as director for re-shoots, replacing Zack Snyder (who retained directorial credit).

Whedon has also worked as a composer (notably for the Buffy the Vampire Slayer musical episode "Once More, with Feeling" and Dr. Horrible's Sing-Along Blog) and comic book writer, both for comic book continuations of television series he created and for established franchises, such as Astonishing X-Men.

Since 2020, multiple actors have accused Whedon of abusive behavior on film and television sets, which he has denied. WarnerMedia investigated Justice League actor Ray Fisher's allegations and announced that it had taken "remedial action" in December 2020.