The Warboys are Immortan Joe's loyal soldiers. War Boys are hand picked at a young age by the guardians of the elevator platform of The Citadel and are indoctrinated as zealots in to Immortan Joe's cult, with Joe as their immortal leader. They are based on the Japanese Kamikaze pilots of World War II.
They are completely loyal, blindly following their leader, Immortan Joe, never questioning the morality of his actions. They view death in service to Immortan Joe as an honor, and seek to die in combat, so they can be reborn in Valhalla as immortal.
The War Boys have very bad health issues, being stricken with diseases like cancer, mostly lymphoma. Due to their ailing bodies and the nature of their actions, a War Boy will not live for a lot of years. Their most notable physical feature is their white paint covering their entire body and black pigment or grease in surrounding their eyes.