Ultear Milkovich

Urtear (ウルティア Urutia) is a female mage who is a very mysterious individual within the series as she is always seen in more then one organization every time the story focus on her. She is the daughter of Ur: Gray Fullbuster and Reitei Lyon's mentor whom thought she had died.

Personality
Not much is shown of her personality, but she regards her mother with cold disdain, classifying her as weak. She was thought dead by Ur.

History
When she first seen, Urtear part of the Magic Council, working as the Inspection Mage under Siegrain.

Garuna Island arc
She later disguises herself as a masked individual named Zalty and joins with Leon to attempt to revive the demon Deliora. The group come into a confrontation with Team Natsu, where she takes on Natsu Dragneel herself though in the end is beaten (though not before Natsu states that, while she in the Zalty guise, she has the scent of a woman). In the end it turns out it was a plot by Siegrain to revive the demon and control it. But since it was long already dead, the mission was a failure. She also ends up getting a bump on her face from the fight with Natsu and mentioning that she didn't even use half her power against him.

Tower of Paradise arc
She later seen during the council situation involving Gerard and the threat of the Tower of Paradise. Both Siegrain and she manipulate the council into firing an Aetherion (a satellite beam of gigantic concentrated magic) at it. The whole thing however is nothing more than a plot by Gerard whose also Siegrain using a psychic projection magic to fool the council, into using the Aetherion to complete the tower and create the R-System, a tower of Lachryma crystals which he hopes to use to revive the Dark Mage Zeref. Once the tower is completed, Urtear uses her magic to destroy the council's HQ and throw them into turmoil.

However, after the events at the Tower of Paradise and Gerard defeated, Urtear revealed her true colors and appeared to have been manipulating Gerard all along, since Zeref was never killed - just sealed away. Her true goal is to unseal Zeref of which she had used Gerard get one of the keys to the seal.

Oración Seis arc
Now, she is a member of the Dark Guild: Grimoire Heart. She along with her other guild mates are searching for the Keys or Zeref, already having one of them in their possession.

Magic and Abilities
Arc of Time: Urtear has been only shown in battle briefly, but she is very skilled. Under the cover of Zalty, during the Garuna Island Arc, she used Lost Magic in her fight against Natsu. Specifically, her branch of speciality is to manipulate the "time" of an object. She can fast forward an object's "time" into the future, making it decay rapidly or rush to attack her opponent. She can even stop time. However, her magic does not directly affect humans.

Since she has used this ability under the guise of Zalty, it is unclear what other abilities she may have. She turned into Zalty with transformation magic like Mirajane uses, but she couldn't fool Natsu's nose, since he could smell a woman's fragrance.

She can also invade the mind of another person, which she did to Gerard to convince him that she was Zeref.

Trivia

 * Urtear's weapon of choice is an teal orb she rolls around on her person.