When "Pretty Little Liars" season 6 returns to the small screen, a new big bad will terrorize the girls. Not much is known about this mystery tormenter except for the fact that he/she is meaner and more dangerous than A.

Series creator Marlene King likes to call the baddie the Uber A, hinting that he/she is much worse than the one that left the Liars scarred for life.

"Mona was original A and Charlotte was Big A. Uber A ends this story," King teased on her Twitter.

While Uber A already sounds nightmarish and murderous, it does not look like the villain will be the ultimate adversary of the girls that "Pretty Little Liars" viewers will ever see in action. This is, at least, what King suggested in another tweet.

When she was asked if there is one "above" the Uber A that the liars will come across, King answered "not in this storyline," hinting that someone much more horrible than the Uber A actually exists and is on the prowl.

It is unclear if the one worse than Uber A will make an entrance in the future seasons of the mystery thriller. But for now, Uber A serves as the final enemy in "Pretty Little Liars" season 6. No one will be pulling the strings as he/she is indeed the final mystery to unravel.

When the latter half of the current season of the series airs, Aria, Hanna, Alison and Spencer will reunite in Rosewood to ultimately put their traumatic Charlotte-filled past behind. Meanwhile, Mona also has some business to take care of in their hometown.

"She, too, is forced back to Rosewood and has a new mystery to face that kind of bonds the five of them together again, whether they want to be or not," Janel Parrish told TV Guide about what character will be up to in the rest of the season.

"Pretty Little Liars" seaosn 6 returns on Jan. 12 on Freeform.