Ilse Langnar was a member of the Survey Corps. 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 a talking Titan she encountered in a notebook that later aided Hange Zoë's research.
Ilse was noted to have resembled Ymir in appearance. She had short black hair that was parted to the right side, lightly tanned skin, and light-colored eyes with a small patch of freckles below each one. She wore the standard Survey Corps uniform and cape with a gray shirt underneath.
Ilse appeared to be quite emotional, yet brave, trying to stand firm in moments of despair. She seemed to be a very devoted and smart soldier. She also cared about her family, seen during her last moments as she regretted not being able to give anything back to her parents. Ilse thought of herself as a proud member of the Survey Corps and was resolved to do whatever she could. Though she took what time she could to document any information she could obtain from the Talking Titan, she lost her level headed attitude when she brought up the subject of eating humans and began screaming at the cowering Titan before running away in fear when it reacts strangely.
Appearance: Ilse was noted to have resembled Ymir in appearance. She had short black hair that was parted to the right side, lightly tanned skin, and light-colored eyes with a small patch of freckles below each one.
Personality: Ilse appeared to be quite emotional, yet brave, trying to stand firm in moments of despair. She seemed to be a very devoted and smart soldier.
Ilse Langnar in the story: During the 34th expedition outside the Walls, Ilse's entire flank is massacred and she is the only survivor. With her horse lost and her vertical maneuvering equipment broken, she abandons her equipment and flees afoot north to a nearby forest, trying to find a route to reach the Walls. Knowing that her chances to make it are very low, she takes out a notebook and begins writing her experiences in the hopes that they at least will be useful to humanity.
How Ilse Langnar echoes later: Later in the Battle of Shiganshina, as Erwin Smith begins to lament the dwindling hopes of his dream, Ilse stands among the many fallen Survey Corps comrades in Erwin's mind, wanting to know if their deaths had meaning.
Source: Attack on Titan Wiki, available under CC BY-SA 3.0.