Rich Ross, Disney Studio Chairman, Quits LOS ANGELES - Rich Ross abruptly stepped down as chairman of Walt Disney Studios on Friday, ending a two-and-a-half-year tenure that was more notable for continued misses than hits. Mr. Ross, a 15-year veteran of Disney, announced his departure to the studio in an e-mail. "I believe in our strong slate of films and our ability to make and market them better than anyone else," he wrote. But, I no longer believe the chairman role is the right professional fit for me. Many people in Hollywood would argue that it was never a fit. Mr. Ross was a star television executive, running Disney Channel, when Robert A. Iger, Disney's chief executive, picked him to turn around the studio in October 2009. He had trouble from the beginning, hiring top lieutenants with little or no movie-making experience; together, Mr. Ross and his team faced the steepest of learning curves. Mr. Iger's hiring of Mr. Ross was heralded as a bold decision. Now his exit marks a rare blemish on Mr. Iger's record as chief executive, partly because of the selection of Mr. Ross but also because the studio continues to be in turmoil more than two years after Mr. Iger first moved to fix it. In recent weeks, according to Disney insiders who spoke on the condition of anonymity because they were not authorized to speak publicly, Mr. Iger began discussions with Mr. Ross about ending the experiment. His exit comes after Disney was forced to take a $200 million write-down tied to the science-fiction megaflop "John Carter." Other misses include "Mars Needs Moms" and "Prom." Mr. Ross scored one smash: "Pirates of the Caribbean: On Stranger Tides." "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," Mr. Iger said in a statement. Disney did not name a successor. It may take weeks or months to fill the job, partly because of a lack of candidates inside the company and across the industry. Two names that Hollywood's chattering class frequently mention as possible leaders for Disney's studio are Kevin Feige, president of Marvel Studios, a Disney unit; and Stacey Snider, chief executive and co-owner of DreamWorks Studios, which contracts with Disney to release its films. Under Mr. Ross, Disney Channel was a franchise-generating machine, generating properties like "Hannah Montana" and "High School Musical." Mr. Ross also played a significant role in the rise of the Jonas Brothers.