The chairman of Walt Disney Studios Rich Ross resigned Friday, a month after the massive box office flop suffered by critically-panned sci-fi fantasy film \"John Carter.\" The 15-year Disney veteran made no reference to the movie -- which lost some $200 million -- in his resignation statement, while Disney overall boss Bob Iger paid tribute to Ross\'s \"business acumen and personal integrity.\" \"For the last 15 years, I have had the opportunity to work with incredibly talented people on behalf of the world\'s best loved brand,\" he said in the statement issued by the entertainment giant,\" the statement said. \"But, the best people need to be in the right jobs, in roles they are passionate about, doing work that leverages the full range of their abilities,\" added Ross, who had been chairman for two and a half years. \"I no longer believe the chairman role is the right professional fit for me. For that reason, I have made the very difficult decision to step down as chairman of The Walt Disney Studios, effective today.\" Iger paid tribute to Ross, saying: \"For more than a decade, Rich Ross\'s creative instincts, business acumen and personal integrity have driven results in key businesses for Disney. He added: \"His vision and leadership opened doors for Disney around the world, making our brand part of daily life for millions of people. \"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.\" Disney has said it would take the huge operating loss on the \"John Carter,\" made by Oscar-winning director Andrew Stanton about a Civil War veteran transplanted to Mars, in its second fiscal quarter. Starring Taylor Kitsch and Willem Dafoe, the movie cost an estimated $250 million, but was met with a chorus of derision from critics when it was released earlier this month. The respected Rotten Tomatoes website said: \"While \'John Carter\' looks terrific and delivers its share of pulpy thrills, it also suffers from uneven pacing and occasionally incomprehensible plotting and characterization.\" It was the first live action movie for Stanton, who won best animated film Oscars in \"Finding Nemo\" in 2004 and \"Wall-E\" in 2009. He also wrote for all three \"Toy Story\" movies as well as \"Monsters, Inc.\"