As an infant, John L. Thunder is given possession of the genie-like "Thunderbolt" during a mystic ritual on his seventh birthday, which was intended to allow the Badhnesians to use Johnny to rule the world. However, the plan is soon aborted after an attack from a neighboring country. Johnny eventually returns to the United States and lives an ordinary life until one day, while washing windows, he inadvertently summons the Thunderbolt with the magic words cei-u (pronounced "say you") which he accidentally uses to become a successful boxer. Johnny underwent several adventures (each time inadvertently summoning the Thunderbolt via the use of cei-u in his day-to-day conversation, never realizing the Thunderbolt was responsible for the extraordinary events that befell him) before finally learning of the Thunderbolt's existence.
Johnny's appearances with the Justice Society of America and in his own solo adventures tended to be quite comedic, as Johnny's main personality trait was being fairly dim-witted, which prompts his much-smarter Thunderbolt to possess a sarcastic (if patient) attitude toward his "boss". Despite recurring impatience with his stupidity, his fellow JSAers genuinely valued Johnny's good-heartedness and dedication and considered him a friend. Furthermore, the Thunderbolt's vast power may have contributed to Johnny's continued JSA membership, his frequent blunders notwithstanding, since the more competent heroes doubtlessly thought it wise to keep an eye on the pair whenever possible. Like most of the JSA members, he had his aging factor greatly slowed during an encounter with the villain Ian Karkull.
Johnny's adventures ceased in the late 1940s when he was replaced in the Justice Society stories by a heroine he had begun teaming up with, the original Black Canary. The reason for his leaving the Justice Society is eventually explained to be that his control over his Thunderbolt weakened due to a spell cast by renegade Badhnesian priests. In the early 1950s, Johnny is kidnapped again by agents from Badhnesia, with the intention of executing their original world conquest plan. Johnny manages to summon Superman, and the would-be conquerors' plans are defeated. Johnny spent some time in Badhnesia afterward, teaching the native citizens about democracy. He returns home after the country elects its first President. Johnny joins the Justice Society on various adventures.
post-Crisis on Infinite Earths
Following the maxi-series Crisis on Infinite Earths was the one-shot Last Days of the Justice Society of America Special. This book depicted the sacrifice of Johnny and his JSA teammates as they left the "new" post-Crisis world and entered into a limbo dimension. Caused by the actions of Adolf Hitler in April 1945, a wave of destruction appears over Earth even as it is settling down from the Crisis. In order to stop a literal Ragnorok, the heroes enter into an eternal battle, and so leave the world.
The absence of the JSA and of Johnny Thunder did not last long. In 1992, DC published Armageddon: Inferno, the mini-series which brought the JSA out of limbo and into the post-Crisis world. This was followed by Justice Society of America (1992-1993). This series showed how the heroes were adjusting to a "normal" life. Johnny is depicted as an overweight man, not as old as his friends, but nostalgic for the past. It is explained that before he had entered into limbo he had lent his foster daughter a few thousand dollars and during his time fighting for the universe, she had created "Peachy's Frozen Yogurt", a very successful chain of which Johnny is half owner... and now very wealthy. Of greater import to Johnny Thunder is his discovery that the Bahdnesians have all but disappeared. A visit to the island of Bahdnesia (now under the ownership of Pol St. Germain) proves that no Bahdnesians are left there. In issue #7 Johnny states:
"There were never very many of them... and the island magic had worn out. T-Bolt was all that was left, and he was with me in limbo. They had to leave or starve to death."
This series also introduced the young Kiku, according to the Thunderbolt, the last remaining Bhadnesian.
After this, Johnny is depicted as suffering from symptoms of Alzheimer's disease. At one point, 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.
When Johnny Thunder began to lose control over his "genie" Thunderbolt, because of declining his mental health, he put the djinn inside an ink pen. Without knowing its danger, Jay Garrick gave the pen to Jakeem.
During a Justice League/Justice Society crossover, when the world was being threatened by an evil Thunderbolt, Jakeem soon discovered that the Thunderbolt actually came from the Fifth Dimension of the original Earth-Two and is controlled by speaking its name (Yz) backwards, cei-u ("Say You"). Jakeem worked with a small group of JSA members, as they attempted to stay alive while Yz and the blue djinn named Lkz battled throughout space. Jakeem even tried to punch out Qwsp, a third Fifth Dimension resident that came to threaten the group.
Qwsp is arrested by Fifth Dimension police. With Captain Marvel's help, Jakeem was able to merge Yz with Lkz. Lkz is controlled by speaking the phrase So Cûl (pronounced "so cool"). Yz and Lkz formed a new purple djinn named Ylzkz and this new djinn is also now controlled by the phrase "so cool".
Jakeem somewhat reluctantly joins the Justice Society of America as a part-time member. Jakeem is welcomed by the fellow young hero, Stargirl, who becomes a friend, and positive influence on him. He also benefits from the guidance of Johnny Thunder himself. He and Hourman (Rick Tyler) also build a brotherly friendship. Like Johnny before him, he often causes trouble by wishing for things without meaning to, due to poorly-worded commands.
During the Last Laugh story arc where certain villains in the DC universe have been affected by the Joker's laughing gas, a Jokerized Solomon Grundy attacks the JSA headquarters. His initial attack involves dropping the head of the Statue of Liberty outside the doors of the JSA and knocking out the then-caretaker of the museum, Alexander Montez. Jakeem and Stargirl are the only two at the headquarters at the time. Their fight against Grundy goes badly, as he steals Jakeem's pen and retreats to the sewers. Jakeem tells Stargirl he wants to get the pen back not because he sees the Thunderbolt as his power, but because the Thunderbolt is his friend.
During the fight with Grundy, Jakeem is nearly knocked out by the behemoth. He realizes Stargirl is in grave peril and in desperation, stretches to reach his pen, just out of reach. A purplish-pink wave of energy appears in his eyes and around the pen, which levitates into his grasp. Jakeem briefly wonders how this has happened, but decides to figure it out later. The fight serves as a bonding experience between the two young heroes. Jakeem has the Thunderbolt fix the statue.
Also in the course of the battle with Grundy, Jakeem unwittingly cures his predecessor, Johnny Thunder, of his Alzheimer's disease. Unfortunately, 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's control. Eventually, Jakeem wrests control of the Thunderbolt back from Ultra, but Johnny Thunder loses his life. Jakeem then wishes that the Thunderbolt could save Johnny somehow, so the djinn chooses to merge with Johnny, creating a new being with the memories of both. He later assumes the name Johnny Thunderbolt. Johnny Thunderbolt bears Johnny's likeness, though it is not clear how the personalities of Johnny and the two djinns interact, and whether any one personality is dominant. Johnny's family is informed of his death and a funeral is held at Valhalla, a cemetery for superheroes. The family does not know that he lives on as the Thunderbolt. The Thunderbolt eventually stops displaying Johnny's likeness while still speaking as him.
At the dawn of the Infinite Crisis, the Spectre shunts Jakeem through his pen into the Fifth Dimension, where he succumbs to the machinations of Qwsp and becomes a mad tyrant. The Thunderbolt amasses an army to fight him, including the Thunderbolt's son, Shocko and Shocko's wife Peachy Pet. With the help of the JSA, Jakeem is freed of Qwsp's evil influence. Among Qwsp's prisoners is Johnny Thunder, apparently separated from the Thunderbolt and living in the Fifth Dimension. Upon the JSA's return from the Fifth Dimension, they find the villain Mordru battling with Nabu. Jakeem jumps the gun and takes action against the evil wizard (who had previously slit Jakeem's throat). Jakeem returns the favor by stabbing Mordru in the throat with his pen, then summons the Thunderbolt, electrocuting Mordru. Jakeem then asks the Thunderbolt to send Mordru "somewhere none of us will ever have to see him again" (followed for the first time by a "please").