Rich Ross stepped down 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.

As the company's studio chief, Ross oversaw production of John Carter, an expensive science-fiction epic whose development started years earlier. The film's costs eventually ballooned to more than $250 million.

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.

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.

Two weeks before his departure, Ross hosted a lavish Hollywood premiere for The Avengers, a big-budget special effects film featuring action stars from Disney's Marvel subsidiary.

Avengers 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

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 were up 34 cents, or 0.8 percent, at $42.42 in afternoon trading on the New York Stock Exchange.

(Reporting By Ronald Grover and Lisa Richwine; editing by Peter Lauria, Andre Grenon, Dave Zimmerman)