It should be obvious to anyone and everyone that Supergirl and Superman are connected by more than just the symbols on the characters' respective chests, but Season 2 is driving that point home in some major ways. Not only will the Man of Steel make his first full and proper appearance, but his mythos will make a big impact on the future of the series. And a set video indicates that Superman will be facing one of his oldest and most popular foes: Metallo.
Now, because we're dealing with unofficial footage that isn't right in the actors' faces, there's the possibility that Metallo isn't involved here, but the chances are quite high. The fight in the video is set on a street that was apparently the setting of an explosion or something, as walls are busted and rubble is scattered, and it shows Superman facing off against said villain. While there aren't any major cyborg features happening with the actor's face, he is definitely wearing a big clue, as it appears to be a piece of glowing Kryptonite strapped to his chest, which is a Metallo trademark. (Watch the video on Twitter here.)
Of course, if that is indeed Kryptonite on his chest, then how is Superman even able to battle him? Because this isn't just some simple slapfight or anything. If the brawl looks anything like this on Supergirl when it airs, then TV audiences will be getting a pretty vicious version of Superman. Based on his fisticuffs, anyway. He is bringing the pain in a great way that looks different from both Zack Snyder's Superman and the fight sequences from Supergirl Season 1. I'm definitely down with this.
First appearing in Action Comics back in 1959, Metallo has gone through several different iterations over the years (usually with the real name John Corben), though almost all of them revolved around a suit of armor that was powered by Kryptonite, at least when he wasn't just mostly robot. Metallo is extremely powerful, making him a solid adversary to what is supposedly the strongest being on Earth. Obviously we're not sure just what version of the character this will be, if it is him at all, but he appears far more human looking than a T-1000, so perhaps that's a clue.
Metallo definitely hasn't just kept to fighting Superman on the comic pages, either. He has appeared in several different animated shows - including Superman: The Animated Series, Justice League, The Batman and more - as well as the DC direct-to-DVD features Superman/Batman: Public Enemies, All-Star Superman and Justice League: Doom. Had Man of Steel 2 happened instead of Batman v Superman, we'd have gotten to see him on the big screen as well.
Metallo also made it to live action on television a few times. The most recent came when Beverly Hills 90210 star Brian Austin Green went bionic for Smallville for a short stint. (No lack of Smallville tie-ins in Season 2.) Scott Valentine took the part in Lois & Clark in the 1990s, while Michael Callan took Kryptonite as his power source in Superboy. Considering we now have Lex Luthor confirmed to exist in this universe thanks to the recent casting of his sister Lena, as well as the presence of Luthor Corp, one has to wonder if Supergirl will have any Superman villains left by Season 3. (Yes, yes it will.)