The actor had previously directed five episodes of FX's Western-themed series and will next guest-star on two episodes this season, EW reports.
Arkin will appear in Episodes 311 and 313, the latter of which is the season finale. He'll play Detroit mafia head Theo Tonin, the boss of Quarles (Neal McDonough) and father of Sammy Tonin (Max Perlich). Justified executive producer Graham Yost tells the magazine that Theo also saved Quarles' life once, "but in a weird way."
Don't expect Arkin to look like his usual self either. "There is a physical tweak that Adam asked for," Yost says. "Adam wanted to be distinctive." The showrunner says he won't be dressed as a pirate, "but he looks cool." We're putting money on a scar or distinctive facial hair.
What do you think mob boss Theo will look like?