The episode is expected to feature Nolan Funk as Felicity Smoak's ex-boyfriend Cooper Seldon, as well as Supernatural's Amy Gumenick, who will play a deranged Arrow fan going by Cupid.
"I always loved the idea of Green Arrow having a crazed fan," Kreisberg told EW. "When I was writing the comic book, my big goal was to create a villain who would last. Cupid has since appeared in the DC Nation shorts on Cartoon Network, and to have her fight our TV Arrow is so much more than I ever could have hoped for the character."
Cupid will appear in the sixth and seventh episodes of the season. The eighth episode will be a crossover with The Flash and the ninth episode will be the midseason finale, directed by Percy Jackson veteran Thor Freudenthal.
The episode will be written by Erik Oleson and Keto Shimizu. Shimizu has been one of the most prolific writers on staff and currently co-writers the Arrow Season 2.5 digital comic with Executive Producer Marc Guggenheim. Oleson is new to the series but will also write the "Corto Maltese" episode before retuning for "Guilty."
Arrow debuts on The CW at 8 p.m. ET/PT on October 8.