Arthur Darvill hasn't been the companion of the Last of the Time Lords since 2012, but his new role is a significant upgrade. Deadline reports that he'll be taking up the role of Rip Hunter, Time Master — quite possibly the coolest-named character in the DC Universe — for the CW's unnamed Flash/Arrow spin-off.
Darvill is best known for his role as Rory Williams in Doctor Who, a character best described as the Doctor's companion's companion, and so it's someone ironic that he's been tapped to play one of DC Comics' most Doctor-like characters.
Rip Hunter is a time traveling adventurer in the pulp fiction style who's managed to remain an obscure but consistent part of the DC Universe for more than fifty years because of his utility as a plot device. Want to get your characters on a time travel adventure, but they don't have a time machine? Have Rip Hunter and his Time-Sphere show up and tell them that they have to come with him now! The future of history is at stake!
He migrated somewhat away from device and into character when he began adventuring with Booster Gold, mentoring the younger hero in safeguarding the timeline and eventually revealing that he was, in fact, Booster's future son. He'd learned everything he knew from Booster, who'd learned everything he knew from Rip, who'd learned everything he knew from... you get the idea. Comics are weird.
The CW's Arrow/Flash spinoff has yet to get itself a proper name, but it was confirmed to be in production this month with the goal of airing in late 2015 or early 2016. The show will feature a core team of superheroes, consisting of some secondary characters from The Flash and Arrow, with rotating guests from around the DC universe. Confirmed to return are Brandon Routh's Ray Palmer (shrinking superhero The Atom), Wentworth Miller's Captain Cold, Victor Garber as Firestorm, Dominic Purcell as Heatwave and Caity Lotz, even though her character, Canary, was killed off at the beginning of the third season of Arrow.
Along with the news of Darvill's involvement, Deadline has confirmed that Ciara Renée has been cast as Hawkgirl, a character who has also never before seen an appearance in live action television, though she's a favorite of fans of the Justice League animated series, where she was voiced by María Canals Barrera.