From Firefly to Castle, these are our picks for the best Nathan Fillion movies and TV shows from the actor's career so far.

In an Instagram post, Nathan Fillion shared his review of Free Guy and noted how much he appreciated Ryan Reynold's work in the blockbuster.

The Suicide Squad killed off a ton of characters... or did it?

James Gunn showed some well-deserved love to his frequent collaborators.

What would happen if all of Nathan Fillion's characters from James Gunn movies were in a Suicide Squad? Fillion knows the answer.

The Suicide Squad actor was once attached to play Nathan Drake in the video game adaptation.

Behold the debut of Nathan Fillion's T.D.K.!

Nathan Fillion plays a lot of serious characters, but he had a lot of fun with James Gunn on The Suicide Squad.

WTF even is a TDK? Let's figure out who the mysterious TDK is from The Suicide Squad, played by James Gunn's real-life buddy Nathan Fillion.

He’s one of the many talented actors in the ensemble.

So don't ask about it.

Let the fan theory continue.

That...that can't be right...

James Gunn (Guardians of the Galaxy franchise) already brings a bit of Marvel superhero experience with him for Warner Bros. DC Comics' flick The Suicide Squad. The writer-director will be taking another crack at the title team of supervillains and has already filled up the roster with quite a few notable names, both from the comics and Hollywood itself. Now it sounds that Gunn will reteam with frequent collaborator Nathan Fillion (Guardians of the Galaxy, Super, Slither) as well as fellow MCU filmmaker Taika Waititi (Thor: Ragnarok, Thor: Love and Thunder), both of whom are joining the cast. Deadline …

Can't wait for this.

A James Gunn favorite is joining his upcoming DC film, The Suicide Squad: Nathan Fillion.

Beloved actor Nathan Fillion - currently appearing on ABC's The Rookie - is reportedly cast in a mystery role in James Gunn's The Suicide Squad.

Famed for starring in the most notoriously canceled television series ever, Nathan Fillion has stamped his mark on a generation. A near-perpetual presence on television for the last 20-odd years, along with popping up in some interesting movies and videogames, ensures he's somebody's favorite part of something. He's reliably engaging and likable to such a degree that whether he's the lead or not, he's going to be remembered fondly. Equally able to be a smooth-talking schmoozer, a befuddled, beset-upon buffoon, and a dozen things around and in between, he's a chameleon you're always happy to recognize.