Walker was a man of medium build with short-cut black hair. He wore the standard uniform of the Survey Corps.
During an expedition beyond Wall Rose, Walker is among Taki's squad when they battle a group of abnormal Titans. Walker is surprised to see that the Titans appear to be herding the soldiers against the nearby cliffside. As Taki leads a counterattack, Walker strays from the group to combat the Titans on his own. He is quickly killed by an Abnormal Titan with transparent flesh.