The comic book world of Iron Fist is depicted here in an image provided by comic book giant Marvel Entertainment Inc. The Walt Disney Co. will complete its .3 billion purchase of Marvel on Thursday and will add a new lineup of superheroes to its empire of characters.

Los Angeles ? Moviegoers have shown a willingness to be entangled by Spider-Man’s web over and over again. Now, as Disney prepares to buy the comic-book powerhouse Marvel, it faces the question of whether fans will also get attached to characters as obscure as Ant-Man and Iron Fist.

The Walt Disney Co. is making a $4.2 billion bet that they will as it nears completion of its acquisition of Marvel Entertainment Inc. this week. The cash-and-stock deal brings those characters and thousands of others to an entertainment empire that already includes Mickey Mouse, Kermit the Frog and Hannah Montana.

Disney’s biggest challenge will be to get enough people enthused about second-string superheroes to justify the price — about $1.2 billion, or 40 percent, more than what Marvel’s stock was worth when the deal was announced Aug. 31.

The high price means Disney will have to find new ways to earn revenue from Marvel — perhaps by bringing Marvel-licensed toys to more store shelves around the world, and by digging deep into its comic vault for potential new blockbusters.

Although Disney is constrained by the fact that big-name Marvel superheroes such as Spider-Man are already locked up in long-term deals with rival movie studios, Disney has had a history of successfully turning unknown talent such as Miley Cyrus, the actress behind “Hannah Montana,” into multibillion-dollar enterprises.

“With Marvel, it’s not just about ‘Iron Man’ and ‘Hulk,”‘ Caris & Co. analyst David Miller said. “It’s all about the other 5,000 characters that you and I don’t even know about yet.”

Disney shares are already being helped, having risen more than 20 percent since the deal was announced, partly on the hope for new character development and better use of Marvel heroes in movies, stores and theme parks.

Marvel shareholders are expected to give final approval to the offer on Thursday, with the closing of the deal to follow immediately.

The deal has already spawned a bout of speculation in the comic book world about who will be the Next Big Thing.

Possibilities include classics such as Ant-Man, the alter-ego of mad scientist Dr. Henry Pym, and Dr. Strange, the mystical go-to guy whenever there’s an extradimensional threat. Both are connected to The Avengers line of characters that Marvel had started developing for the big screen long before Disney made the deal; Iron Man and the Hulk are among the Avengers that Marvel already has tapped.

There are about 5,000 more characters, including obscure ones such as martial arts master Iron Fist from the 1970s and up-and-coming ones such as the Runaways, a street-savvy pack of teenagers that have become a recent Marvel comic-book hit.

Whoever is the next comic book movie star, Marvel has a track record of success: its “Iron Man” movie took in $572 million at box offices worldwide despite the character once being a B-lister in the pantheon of superheroes.

“They picked the right one and they did it the right way,” said Gareb Shamus, whose company Wizard Entertainment Group runs several of the Comic-Con fan conventions around the nation. “When you do that you’ve got a franchise that could last forever.”