Challengers of the Unknown

In the beginning, there was only one... or so we are told. In truth, there was many... a Multiverse of infinite possibilities. After Perpetua was imprisoned by Mar-Novu, Mobius and Alpheus, the Monitor sought to prevent Perpetua from rising again. Of course, there would be another... Mobius betrayed his brothers and became the Anti-Monitor. Mar-Novu, now the Monitor of things to come, would battle Mobius for many eons on his own.

Knowing the Anti-Monitor would eventually awaken and cause infinite destruction, the Monitor recruited five individuals who would gather many others from across the Multiverse. The Monitor would use this team of 52 individuals during the impending Crisis.

The Classic Lineup
The first recruits into the Challengers were the stars of a television game show called the Challengers of the Unknown. The Show consisted of four adventurers: Kyle "Ace" Morgan, Lester "Rocky" Davis, Matthew "Red" Ryan and Professor Walter Haley, all going on strange adventurers. The four men, alongside hostess June Robbins, would become minor celebrities in their time.

The Atomizing.
On October 12th, 1993, the world changed forever when Peter Cannon launched a series of intrinsic bombs throughout the world and framed it on Allen Adams. One of the bombings affected the area of Colorado where the show was filmed. Ace, Rock, Red and Prof. all just seemingly disappeared in a flash of light. June followed the crew to where the disappearences happened but as soon as she arrived, she disappeared too.

Living on Borrowed Time
June and the four Challengers landed in what appeared to be some alternate reality. They are initially approached by a being called the Morelian, who offered them rewards if they could use a Mother Box. Each one of them attempted to use the Box, but it only released Parademons and other monsters, such as a giant stone warrior, a miniture sun and a whirling weaver. After defeating these monsters, the Morelian revealed himself to be the Monitor, who gave them instructions on what to do.

The five set up base in what they call "Challenger Mountain." Challenger Mountain was actually a trans-universal realm created to house the heroes they would be recruiting. During this time, they would encounter such villains as Ultivac, Multi-Man and N'Zrath.

During one mission, the Challengers would meet a man from the future called "Rip Hunter." Rip would join their mission and soon would recruit others that he would sometimes call "Forgotten Heroes."

Finding Heroes
The Challengers started finding recruits by visiting a place sometimes called "New Fabletown." While there, they recruited several individuals, including Bigby Wolf, Snow White, Mary Worth, Boy Blue and Rose Red. Then they traveled to England, where they met up with Mina Murray and Orlando.

Orlando led them to Greg Saunders, who gathered some of his allies before leading them to Sheira Sanders. Sheira and Greg gathered some of their allies, including Sylvester Pemberton and Pat Dugan. The Monitor then intervened and introduced Green Arrow and Red Arrow to the team.

In the months leading up to the Crisis, Some of the miscellaneous alien beings they had encountered joined the team.The Challengers traveled through these Weird Worlds finding as many allies as possible. By the time they had found their 52, the Crisis had begun.

Crisis on Infinite Earths
The Challengers were sent on a series of missions during the Crisis that would contribute to saving the universe. The Seven Soldiers fought to save Earth-2 from the initial strike and Rip Hunter's Forgotten Heroes convinced Darkseid to help. The Challengers all had to then work together to combat the Anti-Monitor's response to them: the Cadre of the Immortal!

Battle For Earth-2
The Monitor sent the Seven Soldiers to Earth-2 along with some of the aliens. During the battle, David Knight was killed and the Cosmic Rod was given to Sylvester Pemberton as an emergency precaution. Oliver Queen attempted to sacrifice himself to let another ship with another billion people escape, but Sylvester Pemberton jumped in and saved Oliver, dying in the process. The Cosmic Rod was split into multiple peices. At least 2 billion lives were saved by Pemberton's actions.

Fight Against the Cadre
The Challengers and the Cadre engaged in direct conflict in Metropolis whilst the more powerful heroes fought at the Dawn of Time. In the months and years after the Crisis, the Challengers would be some of the few individuals to remember the full events of the Crisis.

Challengers from Beyond
After Duela Dent was murdered, Jason Todd and Donna Troy started working together to bring Duela's killer to justice. To confound their efforts, Duela's murderer sent his bounty hunter the Forerunner to stop them. Forerunner failed in this mission, owing largely to the intervention of another Monitor. This Monitor allied himself with Donna and Jason and told them that they must find Ray Palmer in order to prevent the coming of a Great Disaster. This Monitor, called Bob, sought Donna and Jason out specifically, because he knew that they had been targeted by his more aggressive brethren. Bob's ability to teleport from dimension to dimension enabled these Challengers from Beyond the ability to explore strange new parallel worlds.

The first leg of their journey took them to the microscopic reality known as the Nanoverse. Assisting them in this mission was Ryan Choi, who had taken Palmer's place as the Atom. There they learned from a young sorceress that Ray Palmer had traveled the reconstructed Multiverse and residing on one of these 52 worlds. Subsequently, the Challengers fought the evil sorceress Queen Belthera and saw Ryan Choi being forced to summoned back to Ivy Town and replaced by Green Lantern Kyle Rayner.

The Challengers journeyed across the Multiverse, encountering oppositions from both the Monitors and the Monarch. Their journey ended at Earth-51, finding Palmer having replaced his deceased counterpart and married to an alternate Jean Loring. Eventually the Challengers were betrayed by Bob, who sought to kill Ray Palmer, rather than protect him or acquire his aid. Palmer, Troy, Todd, and Rayner then found themselves involved in a war between the Monitors and the forces of Monarch, which led to Earth-51's destruction, before traveing to Apokolips, where they were cought up in a war involving the Justice League, Marvel Family and Harley Quinn.

Through a chain of events from witnessing Brother Eye's failed attempt to control Apokolips, the Challengers and their allies were sent to a reconstructed Earth-51 by Monitor Solomon where the Great Disaster emerged there through the so-called Morticoccus Virus.

After returning to Earth-1 and seeing the death fo Darkseid by Orion, Donna, Kyle, Jason and Palmer decided to team up again. They traveled to the Monitor's headquarters, where they discovered the truth of the Sixth Dimension.

Trivia

 * The Challengers are often divided into mini-teams.
 * Many people often think that "Challengers of the Unknown" only refers to the original five. In fact, the name "Challengers of the Unknown" actually extends to the group as a whole.