Captain Atom has been a part of many of DC Comics crossover events. He has sometimes been a major player but is often just seen in the background. I have not read the majority of these crossovers at the time I am posting this page so please forgive my wikipedish synopses.
(Click on the cover images for more details and images.)
Crisis on Infinite Earths was a 12-issue maxi-series and a 40 issue Pre-Crisis and a 59 issue Official/Unofficial Crisis crossover event, produced by DC Comics in 1985 to simplify its then 50-year-old continuity. The series was written by Marv Wolfman and illustrated by George Pérez (pencils/layouts), along with Mike DeCarlo, Dick Giordano, and Jerry Ordway. The series removed the concept of the multiverse in the DC Universe, and depicted the deaths of such long- standing super-heroes as Supergirl and the Barry Allen incarnation of the Flash.
Millennium was a comic book crossover event that ran through an eight-issue, self-titled, limited series and various other titles cover dated January and February 1988. The limited series was published weekly and was written by Steve Englehart, and with art by Joe Staton and Ian Gibson. Guardian of the universe Herupa Hando Hu, and his Zamaron mate, Nadia Safir, traveled to Earth and announced to the world that they would select ten people who would become the new Guardians of the Universe, and give birth to a new race of immortals. They gathered Earth’s superheroes and sent them to find the chosen persons, who came from various parts of the world. The robotic cult known as the Manhunters (precursors to the Green Lantern Corps) had found a sphere that Harbinger had used to store all the information she had gathered about the universe after the Crisis on Infinite Earths. Because of it, they knew the secret identities of Earth’s heroes, and had planted their agents (including androids, willing human agents, and mind-controlled ones) close to them. On finding out about the search for The Chosen, the Manhunters decided to prevent it, and had their agents reveal themselves and attack the heroes.
Invasion! was a three issue limited series published in late 1988-early 1989 by DC Comics. It was plotted by Keith Giffen, and ties up a great many plot lines from various Giffen-created DC series, including Omega Men, Justice League International, and Legion of Super-Heroes. In this crossover event, the Dominators have put together an Alliance to invade Earth and eliminate the threat posed by their unpredictable “metahumans” (secretly, the Dominators wish to harness this and breed their own army of metahumans, but this goal is kept from the rest of the Alliance, and from some of their own race). After assassinating many former members of the disbanded Green Lantern Corps, and attacking the Omega Men, the Alliance launches a massive attack on Earth, overrunning Australia and establishing there a base from which to conquer the rest of the planet.
The Janus Directive was an eleven-part crossover published between May and June of 1989. Among the creators who contributed to the storyline were writers John Ostrander, Kim Yale, Paul Kupperberg, Cary Bates and Greg Weisman and artists John K. Snyder III, Rick Hoberg, Rafael Kayanan, Tom Mandrake and Pat Broderick. The storyline did not have its own series, but ran through several titles. In this crossover event, Suicide Squad leader Amanda Waller had begun to send her agents on missions in the apparent pursuit of her own private agenda, the so-called Janus Directive, one that brought the Squad into conflict with other meta-human villains and government agencies. So, an all-out mayhem broke loose among these groups, involving various meta-humans associated with the United States military and civilian agencies.
This 1991 mini-series/crossover event Primarily centered on the character Wonder Woman. The storyline was intended to celebrate the character’s 50th anniversary. It was written and drawn by George Pérez. In this series, ancient gods suddenly begin trying to destroy the Earth and each other. While the ancient Roman gods wage war with the Olympian gods, the Egyptian, African, Norse, Babylonian and Thanagarian gods each want to recreate the world in their own images, and attack the super-heroes who stand in their way. Unknown to them, it is in fact the sorceress Circe who has led each of them to wage war on each other, so she can destroy the Earth goddess Gaea.
Armageddon 2001 was a 1991 crossover event storyline that ran through a self-titled, two issue limited series and most of the annuals DC published that year from May through October. Each participating annual explored potential possible futures for its main characters. The creative team behind the series were editor and writer Dennis O’Neil, writer Archie Goodwin and artist Dan Jurgens. This event introduced Monarch, an oppressive tyrant from a bleak, dystopian Earth fifty years in the future. The people were unhappy with his rule, particularly a scientist named Matthew Ryder, an expert on temporal studies, who was convinced he could use his technology to travel back in time and prevent the maniacal ruler from ever coming to power. He learned that in the late 20th century one of Earth’s superheroes had become evil. In the year 2001 this hero had killed all of his comrades, assumed the identity of Monarch, and began his rise to global domination. Because Monarch always appeared in a suit of full body armor his prior identity was unknown. Chosen by Monarch to take part in a time-travel experiment, Ryder traveled back to 1991, the year in which the series was published, and ten years before Monarch’s massacre of Earth’s heroes. Ryder was determined to find out who the Monarch really was and, if possible, kill him before he could rise to power. As he traveled through the rift, his body mutated into a form of living temporal energy, and upon arriving at his destination, he took the name Waverider. DC editors intended for Monarch to be unmasked as Captain Atom and the conclusion of Armageddon 2001 would also mark the conclusion of Captain Atom’s solo series. After news leaked that Cap was the villain, the editors changed his identity at the last minute to Hank Hall (Hawk of Hawk and Dove).
Zero Hour: Crisis in Time was a five-issue mini-series and crossover storyline published by DC Comics in 1994. In it, the former hero Hal Jordan, who had until then been a member of the intergalactic police force known as the Green Lantern Corps, mad with grief after the destruction of his home town of Coast City and having obtained immense power as Parallax, attempted to destroy, and then remake, the DC Universe. The series was written and penciled by Dan Jurgens, with inks by Jerry Ordway.
1995 – Underworld Unleashed
Underworld Unleashed was a three issue limited series published on a bi-weekly shipping schedule from November to December of 1995. The series was written by Mark Waid, with illustrations by Howard Porter, and inked by Dan Green and Dennis Janke. Accompanying the mini-series were four one-shot specials, which featured various DCU characters and expanded upon events taking place within the main series. The story concerns a demon named Neron and his elaborate scheme to steal Captain Marvel (Shazam)’s soul.
The Final Night was a 1996 comic book crossover storyline that ran through a self titled limited series and most of the comics published by DC Comics with a cover date of November 1996 by writer Karl Kesel with pencils by Stuart Immonen. In this series, a young alien woman named Dusk arrived on Earth to warn the population that a giant extraterrestrial being, known as the Sun-Eater, was heading their way. Dusk had attempted to warn hundreds of worlds, prior to Earth, about the Sun-Eater. Each planet had tried, in its own way, to stop the Sun-Eater, but every attempt was as unsuccessful as the last one. Despite her warnings that the Sun-Eater was unstoppable, the Justice League still tried to stop the Sun-Eater aided by Lex Luthor and all of the DC Universe’s heroes.
This crossover event centers on the New Gods of New Genesis and their enemy Darkseid and involves all of DC’s super-powered characters. The storyline introduced the concept of the “Godwave”, an interstellar phenomenon that, on its first pass, created gods on various planets through the universe, such as the Greek, Egyptian, and Norse pantheons on Earth. The Godwave then reached the edge of the universe and bounced back, creating super-humans on its second pass. The series focused on how the wave threatens reality when it rebounds back to its starting point on its third pass. Darkseid attempts to seize the power of the Godwave, which disrupts the abilities of various superheroes, either neutralizing them or drastically altering them. The wave also had the after-effect of making humans feel like something was missing. Some simply think it’s a case of the blues, while others despair so badly they commit suicide. The heroes of Earth and the New Gods of New Genesis battle to prevent Darkseid from accomplishing his plans. Darkseid’s forces again stage an invasion of Earth before travelling to the Source Wall to confront the heroes.
Identity Crisis was a seven-issue comic book limited series from June to December in 2004. It was created by writer Brad Meltzer and the artistic team of penciler Rags Morales and inker Michael Bair. In this series, Sue Dibny, wife of the Elongated Man, is murdered, her body horribly burned. The super-hero community rallies to find the murderer. This leads to the discovery of a cover-up that effects all the super-heroes of the DC Universe.
In Identity Crisis #1, Captain Atom is at Sue Dibny’s funeral and later heads out with Blue Beetle to find Heatwave. He doesn’t have much to do with this series.
Infinite Crisis was a 2005 – 2006 crossover event consisting of a seven-issue limited series written by Geoff Johns and illustrated by Phil Jimenez, George Pérez, Ivan Reis, and Jerry Ordway. The series storyline was a sequel to Crisis on Infinite Earths. It revisited characters and concepts from that earlier crisis, including the existence of DC’s multiverse. Some of the characters featured were alternate versions of comic icons such as an alternate Superman named Kal-L, who came from parallel universe called Earth-Two.
2006 – 52
52 was a weekly limited series that debuted on May 10, 2006, one week after the conclusion of the seven-issue Infinite Crisis. The series was written by Geoff Johns, Grant Morrison, Greg Rucka, and Mark Waid, with layouts by Keith Giffen. 52 also led into a few limited series spin-offs.
52 consisted of 52 issues, published weekly for one year, each issue detailing an actual week chronicling the events that took place during the missing year after the end of Infinite Crisis. The series covered much of the DC Universe, and several characters whose disparate stories interconnect. The story was directly followed by the weekly limited series Countdown to Final Crisis.
On a splash page towards the end of 52 #52, as Booster Gold and Rip Hunter pass through the multiverse, we see an image of the original silver age Captain Atom with Nightshade and Blue Beetle.
2008 – Final Crisis
A crossover storyline that appeared in comic books published by DC Comics in 2008, primarily the seven-issue miniseries of the same name written by Grant Morrison. It directly follows DC Universe #0 after the conclusion of the 51-issue Countdown to Final Crisis weekly limited series. Promotion about the limited series describes its story as “the day evil won”. The series deals with alien villain Darkseid’s plot to overthrow reality, and the subsequent death and corruption of various DC characters and their universe.
2010 – Brightest Day
At the end of another crossover event, Blackest Night, twelve DC heroes and villains were resurrected for some unknown purpose. The events of Brightest Day follow the exploits of these heroes and villains as they attempt to learn the secret behind their salvation.
2014 – Futures End
The five-second sum-up: Starting 35 years into the future of the DC Universe, before moving to five years in the future, Prime Earth is feeling the after effects of a war across the multiverse. As a new threat approaches the vulnerable Earth, Batman Beyond travels back in time to help the heroes of Prime Earth fend off the impending apocalypse.
2015 – Convergence
Set on a world outside time and space, Brainiac has used his access to Vanishing Point to roam the history of the DC Universe. Using it to abduct heroes and villains from the pre-“Flashpoint”, pre-“Zero Hour” and pre-“Crisis on Infinite Earths” eras and across the multiverse, Brainiac amasses a collection of fifty cities, each one placed under a dome and contained on the mechanical world of Telos. Brainiac then opens the domes to see what happens. The ensuing chaos pits various DC heroes and villains and their alternate counterparts against each other as a villain known as Telos arises to take advantage of the situation. Both the Bronze Age Captain Atom and the Modern Age Captain Atom appeared in this series.
2016 – DCU: Rebirth
The event follows the ending of The New 52, a publishing era that rebooted DC continuity in 2011 after the Flashpoint crossover. Its name is taken from the earlier series’ Green Lantern: Rebirth and The Flash: Rebirth, both written by Geoff Johns and focusing on returning their characters to an earlier status quo while updating the premises for new audiences. The initiative is intended to synchronize and harmonize the Post-Flashpoint continuity and the Post-Crisis continuity. The Modern Age Captain Atom has a cameo in the first issue.
2020 – Dark Nights: Death Metal
Following the final battle between Batman and the Batman Who Laughs, the Source Wall is shattered, causing a chain of events that frees Perpetua from her cosmic prison. Despite Apex Lex capturing the Batman Who Laughs, the latter reveals that the future Lex saw was a hoax made by Perpetua in order to manipulate him. After this revelation, Perpetua strips Lex of his powers and returns him to Earth. She starts to get the inhabitants of some of the Earths on her side like the Crime Syndicate of America of the revived Earth 3. Meanwhile, the Justice League survived their battle with Perpetua after they were saved by the Quintessence, who reveal they were protecting something very important. The Quintessence then sent the League to an unknown location in order to search for it. Somewhere, Tempus Fuginaut revised several Earths from the Dark Multiverse and then recruits Wally West to access Metron’s Mobius Chair (which is upgraded with Doctor Manhattan’s powers) and restore the balance between the Light and Dark Multiverses. This action causes Wally to become a new persona and with his new powers, he wants to mend of all of reality into one single timeline, but the presence of the Batman Who Laughs prevents that from happening.
2021 – Infinite Frontier
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