'I Don't Believe It!': Gretel Killeen Revealed As The First 'Masked Singer'

In a reveal that nobody was expecting, Gretel Killeen has stepped out from under the Octopus mask during the 'Masked Singer' premiere.

The sassy '60s cephalopod belted out the theme tune from the hit musical "Fame" to wild applause from the crowd and judges but was ultimately sent home first from the competition after landing in the bottom three with Alien and Wolf.

It was a bittersweet moment learning that we wouldn't get a chance to hear Octopus sing again -- but the departure also meant we'd finally get to see who was under one of those mysterious masks!

Photo: Network 10.

"Oh my god, I don't believe it, it's Gretel Killeen" yelled Osher, as she pulled the giant Octopus head off like a motorcycle helmet and whipped her long hair back.

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The comedian, author and former 'Big Brother' host was the last person the judges were expecting to see -- especially Hughesy who felt particularly betrayed.

Photo: Network 10.

"I was with you only a couple of nights ago, you could have given me a heads up!" he complained.

Which just shows that Gretel has two hidden talents under her belt -- singing and keeping secrets.

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After Osher asked why on earth she said 'yes' to appearing on 'The Masked Singer', Gretel explained why she'd taken on the mammoth challenge.

"Being brave is just one of the greatest qualities you can have, be courageous, push your boundaries," she said.

"I'm buying your album!" Hughesy commented.

Photo: Network 10.

We'd earlier been told that the Octopus had "a hand in everything" and, despite having her career laid out in front of her, had switched gears and followed a different path.

In the clues sequence, Octopus was pictured reading a few lengthy tomes -- a hint about Gretel dropping out of law school before pursuing a career in comedy, radio and TV hosting.

And the references to bookmaking and gambling weren't about horses or casinos but rather about all the actual books that Gretel has written including the 'Fleur Trotter' series.

As for the "pivotal role in a musical that was an international hit"? While Gretel humbly corrected Osher who referred to her as a "star" to explain that she'd been the narrator of 'The Rocky Horror Picture Show'.

Photo: Network 10.

"I don't know if I was the star, that's probably a bit of an overstatement. I was the narrator and I think I was on for three and half minutes but geez, I nailed it".

Just like she nailed her short, but sweet, time playing Octopus.

'The Masked Singer Australia' airs on Mondays and Tuesdays at 7.30 on 10 and WIN Networks.