The actor, who starred as the title character on ABC's crime procedural, admitted to the New York Post that the rushed series finale, which aired in May, wasn't how he would have wanted the story of Richard Castle and Kate Beckett (Stana Katic) to end.
"It wasn't the beautiful send-off that I think maybe you could hope for, but it's the entertainment industry, it's a business, I get it," Fillion said. "I don't take it personally when a show gets canceled -- I can't take it personally, all my shows gets canceled! Look at my resume, it's a long list of canceled TV shows."
Castle ended its eight-season run earlier this year with a tacked-on epilogue to the season finale that showed Castle and Beckett living happily ever after. (The original Season 8 ending was a cliffhanger with Beckett being shot, which was supposed to lead into a planned ninth season.) Katic's contract was not renewed for the ninth season and then ABC canceled the show, forcing producers to attempt to bring the series to a satisfying conclusion that left many fans wanting more.
Fillion remains positive about his overall experience on Castle, however.
"The fact is, I made a lot of great friends on a really great show," he said. "I'm really happy for everything that that show has done for me."