Judge Kelly's stuck-on beauty spot has enthralled admirers for weeks by moving around her face.
But it excelled itself during the semi-finals when it did a total disappearing act ? only to turn up under the right eye of her ACT, Amelia Lily.
Fans of the fast-moving mole have even set up its own Twitter account called @KellysMole and comment about its current position while watching the show.
Puzzled PriyaSonn said: "Why does Kelly's mole keep moving!!??"
Adrianalopez added: "I love how Kelly's mole changes place all the time."
Kelly's mole first took centre stage at the Billboard Music Awards in Las Vegas in May ? on her left cheek.
At the Manchester X Factor auditions in June it had leapt upwards to nestle beside her left eye.
By July 7 the ITV1 show's auditions had moved south-east to London. And the mole had moved south-west to her right cheek.
On November 19 it was even further down her right cheek and a week later it had slipped again and was next to her lips.
Meanwhile, a string of viewers have complained to watchdog Ofcom over Kelly raunchy routine while singing new single Down For Whatever.
The ex-Destiny's Child star, 30, stripped down to a tiny black bra-top and crystal-covered hotpants on Sunday.
Sun readers complained to our website's YourView section.
a4t4 wrote: "It was NOT appropriate for a family show. If Kelly took the sex component out of her routine, I wonder where she would be in the music industry?"
Jasamoah25 added: "Since it was in the evening I found it inappropriate as a family show."
LEGENDARY crooner Tony Bennett says X Factor winners lack the talent to last. He added: "There's a big difference to Nat King Cole, Sinatra or Ella Fitzgerald."