Old Boy was a former colonel in the German Defence Force who participated in World War II. He was given his nickname by those who feared him, along with that of the "Devil," though he was also regarded as a legendary hero. Having been a mentor to several world-renowned soldiers and mercenaries, Old Boy later served in the Navy SEALs anti-terrorist unit Dead Cell at over 100 years old, utilizing his vast cunning and experience. He would often fight with weapons and equipment from World War II, such as the Panzerfaust. Despite his age, Old Boy remained a shrewd man. When the unit was liquidated in late 2008, Old Boy was among the members who were killed.