A key role for Daredevil season 3 has been cast, according to Variety. Wilson Bethel from Hart of Dixie has been cast as a series regular character. We don’t have the specific name for the character, but he is described as “an FBI agent who will play a critical role in the conflict between Matt Murdock and Wilson Fisk, better known as Daredevil and Kingpin respectively.”
At the moment, we know very little about the third season of Daredevil. The end of The Defenders left the character in an interesting place (to remain spoiler-free). There are a couple of different comic specific storylines they could follow, and Variety has a guess as to who Bethel could be playing.
Several months ago, a character description for an FBI agent in “Daredevil” Season 3 leaked. The description led some to speculate that the Marvel character Sin-Eater would be making an appearance on the show. That character was a former S.H.I.E.L.D agent turned NYPD officer named Stanley Carter. Carter, driven mad by an experimental drug, decided to punish those whom he viewed as sinful, even targeting law enforcement personnel like a judge and his own NYPD captain. Sin-Eater was an antagonist for both Daredevil and Spider-Man in the comics.
Daredevil is rumored to start shooting in December and is looking at a 2018 release date, likely after Jessica Jones season 2 and Luke Cage season 2.