Los Angeles  - Johnny Depp may walk away from a fourth installment of Pirates of the Caribbean after Disney ousted the veteran studio chief who first backed his vision for the role of Captain Jack Sparrow, according to the Los Angeles Times.

Studio chief Dick Cook left the company Friday following a string of disappointing box office results and the studio's failure to consistently create popular films for the crucial teenage audience. Disney recently paid 4 billion dollars to buy Marvel Entertainment and gain control of its stable of superheroes such as Spider-Man, Iron Man and the X-Men.

Depp said he was "shocked and very sad" about the ouster of Cook, who started at Disney 38 years ago as a tour bus operator. He told the Los Angeles Times that he only agreed to participate in the Pirates of the Caribbean because of Cook. The three movies in the series have already grossed some 2.8 billion dollars worldwide and Disney announced a fourth installment last week to be called on Stranger Tides.

But given Depp's iconic role in the series, his departure could spell a death knell for the money-spinning franchise.

"There's a fissure, a crack in my enthusiasm at the moment," Depp said. "He's instantly trustworthy. And you generally don't meet people at the studios you trust. I consider Dick a friend in an insane system."  dpa