Britain's Got Talent viewers are depserate to find out who The Witch is - and tonight they might find out.
During the audition stage, the terrifying act left the judges running away, audience members shaking and viewers at home hiding behind the sofa.
In a spine-tingling voice, The Witch asked: "Between the dark and the light, the good and the evil, which will you choose?"
Even 'Mr Nasty' Simon Cowell looked scared as he watched David Walliams and Alesha Dixon take a bite from an apple, then he had to choose between the two placed on Amanda Holden's hands.
Amanda then let out a shriek as The Witch appeared to convulse and turned the apple she didn't bite into a swarm of cockroaches and maggots before disappearing in a puff of smoke.
The judges, including Alesha who had run away from the desk, decided to put The Witch through to the next round and they will compete in tonight's first live semi-fina l.
But who is hiding under that mask? And is it a famous face?
Stephen Mulhern
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One of the strongest theories going around is that The Witch is none other than national treasure Stephen Mulhern.
Stephen is very capable of doing some incredible tricks, having been the youngest member of The Magic Circle when he joined.
"I was thinking Stephen Mulhern in disguise," speculated one fan recently. Another tweeted that it's "probably Stephen Mulhern [as] he's a magician."
Stephen famously hosted Britain's Got More Talent on ITV2 from 2007 until it was scrapped in 2019, so could he be finding any way to ge back on the show? Or is it revenge?
The cheeky presenter has teased that he might be the secretive act by posting a snap with make-up artist Lisa Armstrong, who was previously married to BGT host Ant McPartlin.
Suggesting that Lisa was involved in a potential transformation, Stephen tweeted a picture of him sitting in a make-up chair alongside a snap of The Witch.
He wrote: "Everyone keeps asking if I’m the Witch from BGT! Well you might want to ask Lisa Armstrong what I look like before she put makeup on me!"
But his followers were quick to point out the big giveaway it wasn’t him, with one person writing: “The witch is not you they've brown eyes yours are blue.”
Another added: “The Witch doesn’t have your eyes,” alongside a string of crying laughing emojis.
Noel Fielding
Another name that's been thrown into the mix is Noel Fielding.
The Great British Bake Off presenter loves dressing up in his show The Mighty Boosh and in skits with the bakers.
Celebrity witch and body language expert Inbaal Honigman is convinced she has spotted the clues which point towards Noel, including 'masculine' feet.
"The Witch's enormous boots suggest most likely masculine feet - and the hunched walk shows commitment. This is someone who's happy to remain in character for a long time. Probably a professional actor," she told the Daily Star.
"Never looking at the TV cameras (which is harder than you'd think), this person is likely a pro around TV sets, but the constant eye contact with the judges, and the physical interaction - touching Amanda's hands for example, suggest that this is likely a theatre person at heart, used to intimate shows in front of a responsive audience."
The body language buff believed the mystery contestant could have 'gothic' qualities to them, which led her to Bake Off star Noel.
Inbaal added: "If we're looking for someone in the public eye who is a TV and theatre pro, who can speak in jaunty riddles and has gothy leanings, perhaps one Noel Fielding comes to mind.
"The heavy, worn walking boots are not like the Mighty Boosh star's usual silver pointy footwear... but a lot of other elements fit like a glove!"
Keith Lemon
One theory that's really taking off is that The Witch is in fact Keith Lemon.
The Celebrity Juice star, whose real name is Leigh Francis, spends most of his life pretending to be someone else.
And he's no stranger to prosthetics, having played a number of characters on Bo' Selecta and even a fake version of Amanda Holden's grandmother in their Channel 4 series.
Mark Gatiss
This would be quite the move, but some BGT viewers believe Game of Thrones actor Mark Gatiss is behind the mask.
The Sherlock star, who is known for taking on various roles in the League of Gentlemen, has not responded to the rumours.
Now, fans are convinced Mark Gatiss - the actor and writer and director - could be behind the mask. Viewers have moved to social media and are saying the same thing about the terrifying act which left Alesha Dixon haunted.
"I was convinced that ‘The Witch’ on BGT was you Mark," said one viewer. Another remarked: "That witch was actually (actually) terrifying & a bit Mark Gatiss-like."
"Looks like Mark Gatiss in prosthetics to me [laughing emoji]," commented another fan of the programme.
Others suggested that the act reminded them of something he would produce, with one saying: "Reminds me of a Mark Gatiss creation." Another said it was "Mark Gatiss-like."
Marc Spelmann
It would be rather audacious if Marc Spelmann came back to Britain's Got Talent for a third time.
The talented magician has already auditioned under two different guises - as his own magician act in 2018 and then the following years as the mysterious 'X'.
X refused to speak to the judges, disguised his voice and kept his true identity under wraps during the auditions before revealing himself dramatically in the final.
On why he kept his act anonymous, he said: “It was difficult but at the same time so much fun. We all want to be superheroes, X was a superhero to me.
He added: “X is a concept, I've always loved the notion of an anonymous character that evokes magic from people.
“The most powerful magic you can see is if I can make you do something incredible, that's going to resonate with you so much more.”
He's obviously got previous form at hiding his identity, so some viewers are speculating he has returned once again in a hideous new costume.
"Possibly a new Marc Spelmann character?," suggested one viewer. Another asked: "Anyone else think the Witch is Marc Spelmann?"
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