Ilse Langnar

Ilse Langer (イルゼ・ラングナー) is a deceased member of the Scouting Legion. She was a participant of the 34th expedition beyond the Walls and was in charge of the left wing of the second brigade. She wrote very useful information about her final moments in a notebook.

Personality
She seems to be quite emotional (as shown when she encounters the Titan), yet brave.

During her last moments she mentions how disgusted she was of how she acted during her lifetime.

"All I did was act selfish... I haven't even done anything for my parents who took great pains in raising me. Disgusting.... it's all about to end now..."

She also thought of herself as a proud member of the Scouting Legion and was resolved to do whatever she can.

Story
Ilse was first introduced in a side chapter: Side Story: Ilse's Notebook. She was the sole survivor of a Titan attack. Her horse was killed and her 3D Maneuver Gear was severely damaged to a point she couldn't use it anymore. She ran away on foot to the north, hoping to survive until Wall Maria. She then ran into a Titan who looked strangely at her and started bowing to her and repeating Ymir's name with great respect, mistaking Ilse for Ymir. After Ilse got angry at him, the Titan noticed she was not Ymir and killed her. However, Ilse recorded her interaction with the Titan in a notebook, which was found a year later by Levi and Hanji along with Ilse's Jacket and her Armband which Hanji recognized as the one worn by the members of the 34th Expedition.

Legacy
She is brought up in chapter 20 by Hanji, revealing her notebook is the reason for Hanji's attempts at Titan communication.

Hanji: "First, about attempts at establishing communication. There was a curious precedent with Ilse Langner--"

Ilse's actions are shown to have an effect again in chapter 37 when Mikasa mentions the name Ymir, much to the surprise of Levi and Hanji.

With the discovery of her notebook, the revelation about the name Ymir and her secrets it is also safe to say that Ilse's final written words are of unfathomable value for Mankind.

Trivia

 * It is of note that, when Ilse was yelling at the titan in rage and fear, the titan was crying. This is the first time a non-shifter titan has shown an emotional response.
 * It is also of note that despite her short appearance in the manga, her final words made a major effect on the story.
 * Ilse seems to share more than just appearance with Ymir. The former comments on her selfishness during her lifetime, a trait that is strong within Ymir as well.
 * While Ilse and Ymir resemble each other physically and in personality, it is in Chapter 40 where Ymir not only resembles her, but looks the exact same.Whether or not this has any important meaning has yet to be shown.