Moses

Moses was a member of the Scouting Legion and the first person killed by a Titan at the start of the series. When the Recon Corps squad returns to the District of Shiganshina, his mother starts asking for him, and the Squad leader, gives her all that remained of him—his right arm.

In the manga, his name is Brown, and it is changed to Moses in the anime.

First Appearance
Anime: Ep. 1 "To You Two Thousand Years Later"

(Source: Wikipedia)