With all the trailers and TV spots running for Guardians of the Galaxy Vol. 2, it's easy enough now to remember who the main characters in Marvel's next movie are. As for the supporting cast goes, there are a number of other notable faces we'll be seeing on the big screen, from Glenn Close reprising Nova Prime to Kurt Russell playing Ego the Living Planet. With less than two months to go until Guardians of the Galaxy Vol. 2's release, you'd think there wouldn't be any more casting announcements to make (other than secret cameos, of course), but today it was revealed that Michael Rosenbaum, who spent the better half of the 2000s having a complicated dynamic with Clark Kent as Lex Luthor on Smallville, will show up.

During his appearance on The Adam Carolla Show, director James Gunn reminded folks that Rocky himself, Sylvester Stallone, will appear in Guardians of the Galaxy Vol. 2, but he also took the opportunity to announce that Michael Rosenbaum is getting in on the cosmic Marvel action as well. He said:

We do have a couple of characters who are very important to the Marvel universe who are going to make their debut in Guardians Vol. 2 which people don't know about. Sylvester Stallone plays one of these characters...my friend Michael Rosenbaum also has a pretty decent role in the movie as well, and it sort of works in tandem with Sly's character.

After the broadcast, Michael Rosenbaum expressed excitement on social media that he could finally talk about his involvement in Guardians of the Galaxy Vol. 2 after staying silent for so long.

Besides his time as Lex Luthor on Smallville, Michael Rosenbaum is best known in the world of comic book media for voicing The Flash in Justice League, Justice League Unlimited and Justice League: Doom. He's also voiced Deadshot, Kid Flash and Deadman in various other DC animated projects, but Guardians of the Galaxy Vol. 2 marks his big jump to the Marvel side. Rosenbaum also recently starred as Buddy Hobbs on the Hulu series Impastor.

It's difficult to guess who Michael Rosenbaum is playing in Guardians of the Galaxy Vol. 2, but if James Gunn is saying that the actor has a "pretty decent role," then it sounds we can expect a solid amount of screen time from him. Maybe it will be similar to John C. Reilly's involvement as Rhomann Dey in the first Guardians movie. It's also worth pointing out that Sylvester Stallone is reportedly playing a member of the Nova Corps in the sequel. So if Rosenbaum "sort of works in tandem" with Stallone's character, the first idea that comes to mind is that Rosenbaum is a fellow Nova Corps officer. Alternatively (but less likely) is that he's a criminal Stallone's character is tracking. In any case, if you have your own ideas about who Stallone and Rosenbaum are playing, let us know in the comments below.

Guardians of the Galaxy Vol. 2 hits theaters on May 5.