Klaus was a man of average height and build, with short blond hair. When not wearing the standard Survey Corps uniform, his attire consisted of a button-up shirt and dark pants.
Klaus seemed to be a very straightforward man. While discussing Grisha Yeager's past, Klaus expressed doubts at Grisha's loyalties, sarcastically noting that Grisha should have helped the Survey Corps more if he truly supported them.
Klaus is seen attending a meeting with Erwin Smith and the rest of the Survey Corps' officers to discuss the recent revelations about Eren's father Grisha Yeager. As the officers depart the meeting in high spirits, Erwin informs them he will leave the teams up to them with Klaus reflecting they should keep the task a secret.
Klaus participates in the Survey Corps' mission to retake Wall Maria. After the emergence of the Beast Titan and his forces, Erwin orders Klaus's team to protect the Corps's horses with Dirk and Marlene's teams and Klaus relays the orders to his recruits. During the fighting, Klaus and his fellow soldiers are killed by the Beast Titan, who starts throwing crushed boulders at them, cutting them all to pieces.