For many comic book fans and sci-fi addicts, "Castle" star Nathan Fillion could very well be a superhero himself. Even before he portrayed the charismatic author Rick Castle in the long-running ABC detective series, he already made his mark playing Captain Malcolm Reynolds in the space western science fiction drama "Firefly" and its film continuation "Serenity."

People have looked up to his roles for the longest time, and even though "Firefly" consisted only of one season with a total of 14 episodes, Captain Malcolm Reynolds was an unforgettable character who inspired many individuals.

Given his string of successful characters, Fillion wants to continue portraying memorable roles, and when asked by Comic Book which superhero he would like to give a whirl, he answered: "I think I could take a pretty good crack at Booster Gold. That's kind of my niche... show-offy, vain. I think I could handle that... not too bright."

Booster Gold is a DC Comics character who comes from the future. Just as Fillion said, he likes to show off and wants to seek glory and attention for himself. He uses his vast knowledge on historical events and technology from the future to impress people. Booster Gold manages to grow and develop his character in the comic books, so much so that he even becomes a member of the Justice League, but his attempts for self-gratification often weigh him down.

There is actually a "Justice League" film in the works, but if Booster Gold would not be included in it, then Fillion wants to try out as another character, also from DC Comics.

"I think Ambush Bug. Remember that guy? Little bit off his rocker. You'd never see my face. But I think 'Greatest American Hero' is due for a reboot," he said.

"The Greatest American Hero" is an 80s comedy drama series that starred William Katt and Robert Culp. Meanwhile, the real name of Ambush Bug is Irwin Schwab, a guy with some serious mental problems, which renders him unable to grasp the true extent of reality. In fact, even his real name Irwin Schwab might be a delusion on his part. He might have started out as a villain in the Superman universe, but in the end he decides he wants to become a superhero. People actually perceive him more as an object of irritation rather than threat, and comic book readers either love him or hate him.