Justin Hartley Justin Hartley

Chuck vs. Green Arrow?

Smallville star Justin Hartley will guest-star on Chuck this season, a show rep tells TVGuide.com.

"Couple of days on the show Chuck this week," the actor tweeted Tuesday. "Great people over there. Fun times."

Chuck spies The Matrix's Carrie-Anne Moss

Hartley will appear in the season's second episode as the brother of Jeff Fahey

's character. Fahey (Lost) will play Karl Sneijder, a diamond company boss who has been investigated in the past for criminal activity. He is forced to seek help from Carmichael Industries when his younger brother, Wesley (Hartley) — a Dartmouth- and Oxford-educated anthropologist who has stayed far away from the world of espionage — has been kidnapped by Karl's enemies.

VIDEO: Chuck stars geek out over Star Wars' Mark Hamill

Hartley and Fahey join Carrie-Anne Moss and Mark Hamill as Chuck guest stars on its fifth and final season.Chuck returns Friday, Oct. 21 at 8/7c on NBC.