Nathan Fillion may be done with ABC's "Castle." The actor revealed that he wanted to be cast as the DC superhero Booster Gold when the series is over.

"I think I could take a pretty good crack at Booster Gold," Fillion told ComicBook.

"That's kind of my niche: show-offy, vain. I think I could handle that."

According to Venture Capital Post, Fillion's statement could only mean that he is done playing the role of Rick Castle. The publication speculated that after season 8, "Castle" may just be cancelled for good.

Nathan Fillion is not the only cast member who has expressed his desire to leave the ABC series. Early this year, his onscreen partner Stana Katic (Kate Beckett) also had second thoughts of returning for "Castle" season 8.

"If the character is complete, if there is nowhere else to go creatively, then I think it's better to stop when you're on top," Katic told TV Line.

"For me it's about art over finance, and as long as we're creating something that is compelling and that has somewhere to go, then we're good to go."

When Stana Katic renewed her contract with ABC, the actress denied that what made her stay was the money. She said that when she was presented the storyline for the upcoming season, she felt that her character Beckett had more to offer to the fans.

"Part of my thought process making the decision whether to do another season was creatively, what would that would look like," she told Deadline.

Katic added that she immediately went on board when she saw what would happen between Castle and Beckett in the coming episodes. Her character has also been promoted as Captain, replacing Victoria Gates (Penny Johnson Jerald). Katic shared that her fans should not be worried as inspite of her promotion, Beckett would still be out in the field solving cases.

Tune in for more "Castle" season 8 spoilers, news and cast updates.