The 25-year-old actor was spotted on set for the first time while filming his new movie, American Assassin. since sustaining serious injuries earlier this year during production of Maze Runner: The Death Cure.
The actor suffered substantial injuries while filming a scene for Maze Runner: The Death Curein March -- reportedly suffering multiple broken bones -- and took the next several months to recover. O'Brien was spotted out for the first time in August, and started filming American Assassin in September. Maze Runner will resume production in February, according to Deadline, with the release date pushed back to January 2018.
While O'Brien begins to work on new projects, the show that started his career, Teen Wolf, recently kicked off its and final season.