Deadpool & Wolverine Secretly Gives One Actor Their Fourth MCU Character

Spoilers for "Deadpool & Wolverine" follow.

"Deadpool & Wolverine" is a road trip buddy comedy through the multiverse, where Wade Wilson (Ryan Reynolds) meets many variants of himself. One especially weird member of the Deadpool Corps is Headpool, an undead head from the "Marvel Zombies" universe (he gets around by wearing an automated propeller head). Headpool's voice actor is none other than Nathan Fillion, beloved in geek circles for playing Captain Mal Reynolds on "Firefly" and known outside of them for "Castle."

During the 2000s, Fillion was one of nerds' favorite fancasts to star in a superhero movie – particularly "Green Lantern," a role that instead went to a pre-"Deadpool" Reynolds. (Fillion settled for voicing Hal Jordan in some animated DC movies.) 

While he's not the superhero star his fans wanted him to be, Fillion has popped up in the MCU — three times before playing Headpool, in fact. He appeared in all of the "Guardians of the Galaxy" films, playing a different character in each one. In the first, he voiced a blue alien incarcerated at the Kyln, who takes an unsettling interest in Peter Quill (Chris Pratt) before Groot shuts him up. In "Vol. 2," Fillion filmed a cameo as actor Simon Williams (the future Wonder Man), but his scene was deleted. In "Vol. 3," Fillion got his biggest "Guardians" role as Karja, head of security for the biotech company OrgoCorp. ("Guardians of the Galaxy Vol. 3" is the only MCU movie where you see Fillion's face.)

Fillion's cameos came about because he's buddies with "Guardians of the Galaxy" director James Gunn. He also starred in Gunn's 2006 horror flick "Slither," appeared as T.D.K. in "The Suicide Squad," and will play the hardass Green Lantern Guy Gardner in 2025's "Superman."

If you're worried about Fillion's latest role creating continuity issues, my advice is don't.

Fillion is far from the only actor to play multiple roles in the MCU. Alfre Woodard had a core villain role on "Luke Cage" alongside a bit part in "Captain America: Civil War." Clancy Brown played a minor villain "Daredevil" season 2 and then voiced the fire demon Surtur in "Thor: Ragnarok." Martin Starr had a cameo in "The Incredible Hulk" and then a recurring role in the "Spider-Man: Home" trilogy as Peter Parker's science teacher Mr. Harrington (this was retconned to make them the same character).

Most significantly, Gemma Chan played minor villain Minn-Erva in "Captain Marvel," and then took the lead role in "Eternals" as Sersi. Mahersha Ali, who played the other main villain on "Luke Cage," is set to play Blade in Marvel Studios' reboot of the vampire hunter (if it ever escapes development hell).

I remember fans fretting over whether these actor reuses meant the Marvel Netflix shows were canon to the MCU. This is a symptom of "wiki brain," where every inconsistency in a fictional narrative has to have some sort of textual explanation. It's the same thought process that arrives at a need to "update" Magneto's backstory because any Holocaust survivor would be too old nowadays, overlooking that his Jewishness is a unique quality and that genocides aren't f***ing interchangeable.

I'd look to another science-fiction franchise: "Star Trek," which reuses actors constantly. Jeffrey Combs has played three different major roles in the franchise (slathered in makeup, granted), because he's too good an actor to not reuse. Trekkies just roll with it. I know superhero fans like to tell themselves that their favorite stories are a grand mythology with a will of their own, and that writers just chronicle these tales, but remember: in make-believe, there are no real rules.

"Deadpool & Wolverine" is now playing in theaters.