McGregor- who played Obi Wan Kenobi- confessed the ruse to American chat show host Jay Leno.
The 38-year-old star dressed up in black, with shades and a wig to impersonate the black Sabbath singer.
He showed off photographs of the prank to Leno and said:‘’I just did a lot of shuffling around. They thought I was him. I was delighted.’’
McGregor can currently be seen starring alongside George Clooney in The Men Who Stare At Goats, a big screen version of Guradian columnistt Jon Ronson's book about a US army unit who believed they had special powers.
He can also be seen in the forthcoming Amelia which received its world premiere at the Paris Theater in New York City last week.
The movie which also stars Richard Gere and Hilary Swank focuses onlegendary American pilot Amelia Earheart who disappeared while flying over the Pacific Ocean in 1937.
McGregor who lives in LA recently recently returned home to Scotland to film scenes for The Last Word in Glasgow with Bond Girl Eva Green.
Last updated: 29 October 2009, 11:10
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