Ewan wonders if The Men Who Stare At Goats will break even...with him on boardWill Ferrell and British actor Ewan McGregor head the list of Hollywood's most overpaid stars.

Billy Bob Thornton, Tom Cruise and Jim Carrey also made the top 10 list of actors who cost more to hire than they appear to be worth at the box office.

Ferrell took first place thanks to the summer flop Land of the Lost which racked up an estimated $100m  tomake but earned just $65m worldwide.

Land of the Lost The movie followed disappointing $43m takings for Ferrell's 2008 comedy outing Semi-Pro and $128m for Step Brothers.

Trainspotting and Star Wars stalwart McGregor, who has just appeared opposite George Clooney in The Men Who Stare At Goats, isn't a Hollywood big-hitter...but has recently proved a bad buy.

Using a formula that calculated the actor's estimated salary on each film compared to the film's revenues Forbes.com said that for every dollar Ferrell was paid, his films earned an average $3.29 while McGregor netted $3.75.

To create the list, the financial news website looked at Hollywood's 100 biggest stars who had lead performances in at least three widely distributed movies in the last five years.

Eddie Murphy commanded a high salary after the success of family comedies like The Nutty Professor but recent fare like Meet Dave and Imagine That tanked, taking Murphy to fourth place for earning an average $4.43 for each dollar he was paid, Forbes.com said.