Brook

Keith Shadis

キース・シャーディス
Keith Shadis is the head instructor of the 104th Trainee Squad. He seems to be a friend or have some sort of relationship with Dr. Grisha, as he knows that Eren is the son of the doctor and praises Eren for his effort. First Appearance Manga: Ch. 15 "One By One" Anime: Ep. 1 "To You Two Thousand Years Later" (Source: Attack on Titan Wiki)