Halle Lidner
From Death Note Wiki
Halle Lidner (ハル・リドナー, Haru Ridonā), whose real name is Halle Bullook (ハル・ブロック, Haru Burokku), is a former Secret Service agent who works for Near as part of the SPK, and is the only female member of this organization. She joined the SPK to avenge one of her relatives who has been killed by Higuchi at the time when he acted as Kira.
She states being on neither Near's or Mello's side in the competition to catch Kira, and even leaks information to Mello about the investigation, as her only purpose left is to catch Kira.
She was chosen over Gevanni to infiltrate the bodyguard unit that protects Kiyomi Takada, with the purpose through her to get more information about Kira. In order to attain her trust, Lidner acted out the role of a diligent handler while covertly trying to uncover the connection between Takada and Kira. Her position as bodyguard of Takada, as well as her beauty, made of her a very popular figure, right behind Takada in terms of popularity. In the one-shot chapter set three years after Light's death, it is revealed that she and Rester continue to work with Near.
Although not stated, Lidner seemed to somewhat care for Mello. Although she was ultimately working for Near, she appeared to share more information with Mello than Near was aware of. Also, when Lidner realized that Mello was inside the burning vehicle (and dead), she thought, "Oh no...Mello..."

