“Castle” star Nathan Fillion may be a god among geeks, but he’s not a superhero. You know who is? Robert Downey Jr., a.k.a. Iron Man. But maybe the two men are more alike than you’d think — they both play attractive, rich playboys who like to solve crimes alongside sexy, tough women.

In a cute display of corporate synergy — ABC’s “Castle” and Marvel are both Disney-owned properties — Fillion and Downey teamed up for a commercial promoting the upcoming summer blockbuster “The Avengers.”

“You know what, Robert, I couldn’t help but notice how similar our characters are,” Fillion tells Downey. “On ‘Castle’ I play a hero, in ‘The Avengers’ you play –“

Wild guesses? “A hero,” Downey interjects.

“Right. I play the wealthy, charming philanthropist,” says Fillion. “As do I, me too,” Downey responds.

The one difference? “I’m Iron Man, and you’re not,” Downey points out.

Hey, you can’t argue with facts.

Posted by:Jean Bentley