Hollywood superstar George Clooney has laughed off rumours he is set to return to the long-running U.S. medical drama ER for its final season. Reports alleged the 46-year-old was one of the former stars of the hit series due to make a small-screen comeback to celebrate the hit show ending after its 15th season later this year (08). But Clooney - who shot to fame with his portrayal of hunky Dr Douglas Ross - has dismissed the claims, insisting the series' bosses have not asked him to come back. And the actor wasn't the only one shocked by the rumours of his return - he claims the show's executive producer John Wells had no idea of his supposed cameo appearance either. He explains, "No, we never even talked about it. No one has ever asked me. It's the funniest thing. The story came out, and I was like, 'Where did that come from?' It was everywhere - I mean in one day! "I ran into John Wells two days ago on the lot and said to him, 'What the hell happened?' He said, 'I don't know. I don't know where that came from." But Clooney isn't discounting how crucial the role was to his catapulting him to stardom, adding, "I was 33 when ER hit, so I have a very different outlook on the way things work. "I don't think I was supposed to have been famous. I realize how much of this is luck."