VIDEO : Nathan Fillion Thanks 'Castle' Fans After Finale

Nathan Fillion's crime drama, "Castle," signed off for the last time Monday night, ending its eighth season just days after it was announced it would not be returning for a ninth. The actor himself was even around on Twitter to live-tweet the entire thing. Fillion then ended the night with a special note to his fans, writing, "Well. That's it. Thank you, everyone. What an incredible journey. Mic drop. Castle out." The production staff behind the show reportedly shot two versions of the finale -- one for if it was renewed for another year and one for if it wasn't. But even if the show had continued, the program's main co-star Stana Katic would not have been around as her exit from the show was announced last month.