Joseph Hill "Joss" Whedon (English: Joseph Hill "Joss" Whedon, /ˈwiːdən/; born June 23, 1964) is an American screenwriter, director, producer, comic book author, and composer. He is best known as the creator of several television series: the supernatural drama Buffy the Vampire Slayer (1997–2003) and its spin-off Angel (1999–2004), the short-lived space western Firefly (2002), the internet musical Dr. Horrible's Sing-Along Blog (2008), the science fiction drama Dollhouse (2009–2010), the Marvel Cinematic Universe film The Avengers (2012) and the series Agents of S.H.I.E.L.D. (2013–2020), as well as the science fiction drama The Nevers (2021).

After starting his career in sitcoms, Whedon wrote the poorly received horror comedy Buffy the Vampire Slayer (1992), which he later adapted into the acclaimed television series of the same name, co-wrote the screenplay for the Pixar animated film Toy Story (1995), and wrote the science fiction horror film Alien: Resurrection (1997). Having achieved success as a television showrunner, Whedon returned to film to write and direct the sequel to Firefly, the film Serenity (2005), co-write and produce the horror comedy 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 superhero film in the DC Extended Universe Justice League (2017), for which he also served as director of reshoots, replacing Zack Snyder (who retained directorial credit).

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

Beginning in July 2020, several actors, producers, and writers spoke out against Whedon due to the toxic work environment that they alleged he created on many of his projects. Whedon denied any wrongdoing, while acknowledging that he can be "confrontational".