When the girls return to Rosewood for the upcoming winter premiere of "Pretty Little Liars" season 6, they will be welcomed home by a new villain who is set to make their lives more miserable than before.

Show creator Marlene King told Hollywood Life back in October that "the new big bad" was different from "A," the slippery antagonist whose identity remained a secret until the very end. Viewers learned that Hanna (Ashley Benson), Emily (Shay Mitchell), Spencer (Troian Bellisario), and Aria's (Lucy Hale) tormentor was Cece Drake (Vanessa Ray). Cece was actually Charlotte, the older sister of Alison (Sasha Pieterse) and Jason (Drew Van Acker).

In the second half of season 6B, the new killer is reportedly from a different mold than "A." Some of the "Pretty Little Liars" fans call him/her "B." Instead of playing tricks on the Liars, this one prefers a more direct method. To get the girls' attention, he/she will go on a killing spree in Rosewood.

"The new big bad — I won't say if it's a he or a she. We think it's a he right now, but you never know. The new big bad is more lethal. The new big bad isn't playing a game. The new big bad has an agenda and will not stop at anything before that agenda is taken care of," King said.

Meanwhile, Bustle has an interesting theory on the identity of the Liars' new nemesis. According to the website, "B" is none other than Jason. The other DiLaurentis sibling has reportedly become unhinged after learning that the girl he dated before was actually his sister Charlotte. It is possible that Jason is angry at Alison and the girls for being kept in the dark for a long time.

"Pretty Little Liars" season 6 airs Tuesdays at 8 p.m. EST on Freeform (formerly ABC Family).