New characters were shown in the new trailer of "Avengers: Age of Ultron," including the mystery woman inside the cave.

There are rumors that she could be T'Challa's younger sister Shuri, who later on adopted the identity of the Black Panther as reported by Comic Book.

Another speculation is that she could be a Dora Milaje, a personal bodyguard of Black Panther.

Unfortunately, both speculations are wrong because a new source finally unveiled the identity of the mystery woman.

Schmoes Know reported that the new character that was featured in the "Avengers 2" new trailer is Mantis. According to the website, Marvel needs to find a way to connect the cosmic universe teams of the Guardians and the Avengers.

Their source revealed why Mantis could be the key to the crossover of both superhero teams.

"This would seem to make a lot of sense as she 1) has direct ties to Thanos, 2) has even stronger ties to Vision, Quicksilver, and Scarlet Witch, 3) has a personal vendetta in the comics against Klaw and, most importantly 4) has been a prominent member of both The Avengers and the Guardians of the Galaxy," the insider said.

Speaking of Klaw, Schmoes Know also confirmed that Andy Serkis will be playing the role of the supervillain. The website reported that the version of Ulysses Klaw will be the combination of both the human physicist and his father Fritz.

However, there isn't any reports yet as to who will portray that role.

"Fritz could possibly have a small appearance in the film or a passing reference, but most of his attributes will be given to Serkis' Klaw," the insider said.

Since, we already know who the mystery woman is in the new trailer of the "Avengers: Age of Ultron," then maybe the next character that will be revealed is the woman behind Thor in the footage. Could she be the Enchantress, who is one of Thor's greatest enemies?