Walt Disney Studios Chairman Rich Ross (L) and Walt Disney Company President and Chief Executive Officer Bob Iger pose together at the world premiere of Disney Pixar's "Toy Story 3" at the El Capitan Theatre in Hollywood, California in this June 13, 2010 file photo.[Photo/Agencies]

LOS ANGELES  - Rich Ross resigned under pressure as chairman of Walt Disney Co's movie studio after a less than three-year run that included the release of "John Carter," one of the biggest flops in recent Hollywood history.

Ross, named to the job in October 2009, was never able to duplicate the success he enjoyed as president of the Disney Channel, where he was credited with creating monster franchises that included "High School Musical" and "Hannah Montana."

"I no longer believe that the Chairman role is the right professional fit for me," Ross told his staff in an email.

Disney will not immediately name a new head for its studio, a source familiar with the matter said.

In a statement, Disney CEO Bob Iger said: "For more than a decade, Rich Ross' creative instincts, business acumen and personal integrity have driven results in key businesses for Disney. ... I appreciate his countless contributions throughout his entire career at Disney and expect he will have tremendous success in whatever he chooses to do next."

Ross kept a low profile at the Disney Channel and never adapted to Hollywood glad handing, according to a source with knowledge of his style. At the April 11 premiere for Disney's big budget film "The Avengers," the studio chief stood off to the side while the movie's stars chatted up other executives.

Ross lost the confidence of Disney's big name producers, including Jerry Bruckheimer, who produced its "Pirates of the Caribbean" movies, said one person with knowledge of the relationship. Last summer, Ross shut down production of Bruckheimer's big budget film "The Lone Ranger" over budget issues and cut its $250 million budget to $215 million.

The studio executive took the heat for letting the "John Carter" budget rise to $250 million from $200 million, said one person with knowledge of Disney thinking, and for its lackluster marketing effort. Ross killed another big budget film, a remake of "20,000 Leagues Under the Sea," but let "John Carter" production begin.

Disney said in March it expected the film to lose about $200 million and to saddle its studio with $80 million to $120 million in operating losses.

The swiftness of Ross' resignation leaves Disney without an obvious successor for the job.

Marvel Studios president Kevin Feige and Ross' lieutenant, Walt Disney Studios president Alan Bergman, are long shots to replace Ross. Disney will likely look for a candidate outside its house.

Ross "was a superstar at the Disney Channel, and the results at the studio have not been exceptional," said Evercore Partners analyst Alan Gould. Still, he said Ross' exit was a surprise given his earlier success in Disney's cable business.

Ross joined Disney Channel in 1996 as a programming and production executive and was promoted to president of the cable channel in 2004. His success at the Disney Channel made him a rising star in the company and eventually led to his being hand-picked by Iger to replace long-time chairman Dick Cook, whom Iger forced out, as head of its film division.

Ross had few big hits during his tenure. "Pirates of the Caribbean: On Stranger Tides" was a global smash, but part of an established franchise. He also made waves when he picked a Hollywood outsider, M.T. Carney, to run film marketing for Disney. She left the studio earlier this year just as "John Carter" was completed.

Ironically, Ross could have his biggest hit when "The Avengers" is released in the United States on May 4.

The film, featuring action stars from Disney's Marvel subsidiary, is expected to be one of the year's biggest hits. Opening weekend sales may reach $155 million in the United States and Canada, according to Boxoffice.com.

For investors, the departure of Ross should have little impact, analyst Gould said. Disney's results are driven by its much-larger theme-park and cable network businesses.

Disney shares gained 27 cents, or 0.6 percent, to close at $42.35 on the New York Stock Exchange.