Nathan Fillion Joins Percy Jackson: Sea of Monsters as Hermes - MovieWeb.com It's just been announced that Nathan Fillion will play Hermes in the sequel to Percy Jackson and the Olympians: The Lightning Thief. After being disappointed by the first one, I wasn't excited to see this sequel. However Nathan Fillion is one of my favorite actors and I am a huge fan of the book series. They need to somehow work in some of the most important things they left out in the first one to help the overall story. If this one fails they need to reboot it and have the movies follow the books closer. I didn't hate the first film, I thought it was highly entertaining standalone movie, but it was a poor adaptation.