Whedonverse appearances: Firefly as Captain Malcolm ‘Mal’ Reynolds; Buffy the Vampire Slayer as Caleb; Dr Horrible’s Sing-Along Blog as Captain Hammer; Much Ado About Nothing as Dogberry.
Marvel appearances: Guardians of the Galaxy as Monstrous Inmate; Guardians of the Galaxy Vol. 2 as Simon Williams.
Another of Whedon’s long-term favourites is Nathan Fillion, most recognisable from Firefly but also a bunch of the writer’s other projects. He is also a frequent collaborator with James Gunn, who cast him as a CGI alien in Guardians and will work with him again in Guardians Vol. 2.
Whedonverse appearances: Buffy the Vampire Slayer/Angel as Wesley Wyndam-Price;
Dollhouse as Senator Daniel Perrin; Much Ado About Nothing as Benedick.
Marvel appearances: The Avengers/Guardians of the Galaxy as The Other.
Just like Nathan Fillion, Whedonverse favourite Alexis Denisof also appeared in the MCU as an unrecognisable alien. This time, Denisof played the servant of big bad blue being Thanos in The Avengers. He was then murdered by Ronan the Accuser in Guardians of the Galaxy.
Whedonverse appearances: Angel: ‘Somnambulist’ as Penn.
Marvel appearances: Thor/The Avengers/Avengers: Age of Ultron/Captain America: Civil War/Avengers: Infinity War as Clint Barton/Hawkeye.
Jeremy Renner’s role as superhero Hawkeye, founding member of the Avengers, needs no introduction. You might not know, though, that Renner appeared back in Angel season one as an evil vampire apprentice of Angellus.
Whedonverse appearances: Buffy the Vampire Slayer/Angel as Spike.
Marvel appearances: Runaways as Dr Victor Stein.
Though he only worked with Joss Whedon in the two Buffyverse shows, James Marsters’ Spike is one of the definitive Whedonverse actors. After several voice parts in Marvel cartoons over the years, Marsters will join the MCU in new TV show Runaways, as villainous father Dr Victor Stein.