Studios invest in stars for the same reason they invest in best-selling books or comic books (though stars cost a lot more), Gittes says.

FORBES: The Myth Of Stars

While Lee, Nimoy and Carrie Fisher are the big draws at this year's event, the Dallas Comic Con also features stars of the hit American television series "The Walking Dead, " John Romita, Jr.

CNN: STORY HIGHLIGHTS

Now that Lee is currently starring as himself in a new Archie comic book, The Mighty 7, this begs the question, if Lee stars in the movie about the comic book, who will make the cameo appearance?

FORBES: Stan Lee Isn't Crying Over Lost 'Avengers' Profit

An older, rebellious man who works at the network stars in a broadly comic TV show that electrifies the nation by making a mockery of England's dictator, yet he's confident he won't be fired -- an inexplicable misjudgment on his part for what was obviously seditious conduct.

WSJ: 'Vendetta' Is Violent and Vapid

As studios have focused increasingly on special effects-laden films built around pre-sold characters from comic books and the like, action stars' place in the firmament is vastly diminished.

WSJ: Arnold Schwarzenegger: A Career Not Yet Terminated

The Fox film attracted three big stars who could play up the comic potential of the story: Jack Black, Steve Martin and Owen Wilson.

FORBES: Entertainment's Biggest Turkeys of 2011

These days, when Mr. Schwarzenegger promotes a film, such as when he participated in a Comic-Con International panel with his "The Expendables 2" co-stars including Sylvester Stallone and Randy Couture, his handlers still prep him as they would have in office, quietly slipping him note cards to review backstage.

WSJ: Arnold Schwarzenegger: A Career Not Yet Terminated

And, even on the big screen, where so many TV stars before her have gone down in flames, Aniston is a highly enjoyable comic actress.

CNN: Not nearly a 'Perfect' picture, but agreeable

The Brummie comic's most recent success is the police spoof The Detectives, in which he co-stars with Robert Powell.

BBC: News | UK | Comedian's daughter saved by kidney transplant