'The Flash': Who Plays Anton Slater?

The Flash returned from midseason hiatus tonight and introduced a pretty unique piece of legacy casting in the process.

Spoilers for tonight's episode of The Flash, "The Trial of The Flash", below!

As the title suggests, tonight's episode sees Barry Allen/The Flash (Grant Gustin) being taken to court after being framed for the murder of Clifford DeVoe/The Thinker (Neil Sandilands). The district attorney who prosecutes Barry's case is Anton Slater, whose face some DC fans are sure to recognize.

Slater is played by Mark Valley, who was best known for playing the title character on Fox's Human Target. The DC Comics-inspired television series followed Christopher Chance, a security expert who would protect clients by secretly infiltrating their lives. The series aired between 2010 and 2011, and acquired a devoted fandom over that period of time.

While Human Target might not be the most memorable DC Comics property, fans of the series are sure to be happy to see Valley return to the DC TV world. It also marks the second Human Target-related reference to enter the Arrowverse in as many years, after Will Traval played Christopher Chance on an episode of Arrow.

This is just the latest example of "legacy casting" -- casting former DC media actors -- that the Arrowverse has brought on screen. The Flash has included quite a few alums from the 1990s Flash series, including John Wesley Shipp, Mark Hamill, Amanda Pays, and Alex Desert. Supergirl has introduced quite a few more, with everyone from Lois & Clark: The New Adventures of Superman's Dean Cain and Teri Hatcher to Smallville's Erica Durance having some sort of role on the show.

"We love it, and we think the fans love it," Supergirl EP Robert Rovner said late last year. "We love seeing people that we know and are familiar with step into other roles. And what's great about them is that they're all wonderful actors as well. So, you get the excitement of seeing them in the new role but they also bring a lot when they take on these new characters."

The Flash airs Tuesdays at 8/7c on The CW.