Dirk Reiss (ディルク・レイス Diruku Reisu?) was the youngest son of Rod Reiss and Lady Reiss, the younger brother of Frieda and Urklyn Reiss, the older brother of Florian and Abel Reiss, and the youngest half-brother of Historia Reiss.
Dirk was a young boy, 14 years in age. He had shaggy black hair and bright eyes just as his father and brother Urklyn did. He had been seen wearing a simple, light colored robe, a dress shirt, and a pair of black pants, as was common among the males during the Reiss family gatherings.
In the year 842, Dirk Reiss watched the death of his uncle Uri Reiss, who inherited the First King's power to his older sister Frieda Reiss. When Frieda's Titan form tried to eat his uncle Uri, he was silently watching the whole scene with other Reiss family members.
In the year 845, when Wall Maria fell, Grisha Yeager invaded the Reiss home territory. He then transformed into a Titan and killed most of Reiss family members including Dirk himself. According to Rod Reiss, he was crushed by Grisha's hand, along with his younger sister Abel.