Yz is a 5th DimensionJinn who resided in a pen that was entrusted to Johnny Thunder on his birthday where the Badhnesians would use it to rule the world. This plan was thwarted when Badhnesia was attacked by a neighboring country. Later on, Johnny Thunder became aware of Thunderbolt's existence and the summoning word "cei-u." In the early 1950s, Johnny is kidnapped by the Badhnesians with the intention of executing their original world conquest plan. With help from Thunderbolt, Johnny manages to summon Superman and the would-be conquerors' plans are defeated. During Johnny Thunder's time with the Justice Society of America, his control over Thunderbolt was weakening due to a spell cast by Badhnesian priests. When Johnny Thunder started suffering from symptoms of Alzheimer's disease, he loses track of a pen in which the Thunderbolt is being stored. The pen eventually ends up in the ownership of a young African American boy named Jakeem Williams, who takes up the name Johnny Jakeem Thunder or Jakeem Thunder. In a later battle with Solomon Grundy, Jakeem unwittingly cures Johnny Thunder of Alzheimer's thanks to Thunderbolt. However, Johnny immediately falls prey to the Ultra-Humanite, who takes over Johnny's body in order to command the Thunderbolt's powers. In the "Stealing Thunder" storyline, Jakeem is one of several heroes left free from Ultra-Humanite's control. Eventually Jakeem wrests control of the Thunderbolt back from Ultra-Humanite, but Johnny Thunder loses his life. Jakeem then wishes that the Thunderbolt could save Johnny somehow, so the genie chooses to merge with Johnny, creating a new being with the memories of both. He later assumes the name Johnny Thunderbolt. In the "DC Rebirth" reboot, it was mentioned that Johnny Thunder lost Thunderbolt after Joseph McCarthy had him reveal his secret. In the "Watchmen" sequel "Doomsday Clock," Thunderbolt returned when Doctor Manhattan undid the experiment that erased the Justice Society of America and the Legion of Super-Heroes. He was once again merged with Johnny Thunder to become Johnny Thunderbolt.
Thunderbolt is featured in Stargirl. He and Johnny Thunder are shown to be members of the Justice Society of America. When the Injustice Society attacked the JSA, Thunderbolt was left trapped in his pen for ten years while Johnny Thunder was killed by Brainwave. According to Pat Dugan, Thunderbolt was a dangerous weapon.
