The 27-year-old Sandymount native will star in Black Ice.
The film tells the story of 20-year-old Alice, who is trying to deal with the aftermath of a devastating car crash that took the life of her brother and left his girlfriend in a coma.
The film is a dark story set against the economic crash in Leitrim.
It's going to be a big year for Killian next year with another series of Love/Hate gearing up to go into production.
And with Darren out of the picture, his character Tommy could well become Irish women's "on screen crush".
If they can find it within themselves to overlook that disastrous haircut, that is.
Talking about his dodgy do, Killian said it was all part and parcel of acting. "All these things help; a huge part of the process for creating a character comes down to costume, hair, make-up.
"I had this kind of hair when I was 14. I don't know why I thought that was a good look."
The cast of Love/Hate are letting their hair down since the series drew to a brutal and bloody close on Sunday.
Peter Coonan (28) aka Fran the Man and co-star Laurence Kinlan (29), who plays cowardly Elmo, recently enjoyed a night out with model and Horse Outside star Madeline Mulqueen (21).
Madeline posted pictures of herself with the lads which show them posing for the camera and having a good few laughs. "Banter with Fran the Man and Elmo," she wrote.
Killian is one of fellow actor Coonan's closest friends. "We're very close," Killian said. "We've known each other for years."