's Sean Maher will join his old co-star Summer Glau on Arrow this season, says The Hollywood Reporter.
Set to appear in the series's upcoming tenth episode, Maher will appear as Mark Scheffer, better known as DC Comics supervillain Shrapnel. In the Arrow-verse, Scheffer will be a serial bomber who places Starling City in a grip of terror and threatens the life of Sebastian Blood.
Odds that he's a plant employed by Brother Blood himself? Probably about even.
Maher's character is one who, in the comics, definitely crosses the line into super-powered villains. It seems likely the first appearance will be one where he doesn't have that appearance, though--perhaps it'll be in The Flash that we see the more traditional look for Shrapnel.