Answer by Thaddeus Howze:
There's more to it than just the publication date…
It would be so easy to just say, look at their publication dates and say Ant-Man is a ripoff of The Atom and be done with it. Rather we should look at the characters and see how each evolved considering how they began.
Both characters are born of the Silver Age, when the comic industry was struggling to reinvent itself. DC and Marvel were experiencing an explosion of new ideas and were trying to capitalize on what was becoming a renewed interest in superhero-related comics.
Both heroes were "science heroes." A class of heroes of that era, replacing the grim and gritty Westerns which saved the comic industry during their doldrums but now needed to fall by the wayside, allowing heroes who used science and technology to usher in a new age.
With the World's Fair coming to New York in 1964, these canny businessmen wanted to be take advantage of everyone's renewed interest in science. Note the number of scientifically based famous heroes from that same era.
Marvel Science Heroes and Villains
- Fantastic Four, Reed Richards
- Iron Man, Tony Stark,
- Black Panther, Prince Tchalla,
- The Hulk, Bruce Banner,
- Spider-Man, Peter Parker
- Doctor Octopus, Otto Octavius
- The Eternals – an entire race of scientific supermen
DC Science Heroes and Villains
- Atom as Ray Palmer,
- the Flash's police forensic scientist, Barry Allen,
- Bruce Wayne's everyman's scientist Batman,
- The Chief from the Doom Patrol,
- Dr. Magnus from the Metal Men,
- Lex Luthor, supergenius, businessman, criminal
- Metron and the New Gods – another entire race of scientific supermen
There was an explosion of science, technology and ideas revolving around how science could change the world. Unfortunately, most of the writers of Marvel and DC were NOT scientists, so their science left much to be desired.
Of all the "science heroes" both Henry Pym (Ant-Man) and Ray Palmer (Atom) have had some of the longest running and most challenging careers of the science hero in their respective universes, partially because they were both brilliant and troubled individuals.
The Atom: Legacy hero of the Golden Age
A character called the Atom began his career in comics in the 1940s as a member of the Justice Society. This Atom, Al Pratt, had no powers other than his fighting prowess and take no prisoner's attitude in a fight. A "tough guy" he was a self-made man, trained to pugilistic excellence by retired boxer, Joe Morgan, the same man who would train another fighting "tough guy"known as Wildcat. Pratt would at the end of his career briefly gain superhuman powers through a "radiation accident" fighting a villain named Cyclotron.
When the Golden Age ended, DC Comics decided they wanted a new Atom but not based on the ideas of the old one. They decided to try creating a superpower rarely seen in comics; shrinking.
The Silver Age Atom is a fictional superhero appearing in comic books published by DC Comics. Atom was created by editor and co-plotter Julius Schwartz, writer Gardner Fox and penciler Gil Kane. He was one of the first superheroes of the Silver Age of comic books and debuted in Showcase # 34 (Oct. 1961).
Enter Ray Palmer, physicist; he would explore the nature of a white dwarf star and its intense molecular density. He would create a technology that would let him reduce his molecular density while controlling his weight. He would have the ability to deliver a full strength, full mass punch while being at what would be his nominal size of about six inches tall. Against normal humans, this would have the force of a bullet.
The fun started when the writers decided there could be adventures to be had if the Atom could shrink even further. What if he could shrink to the size of a insect, a dust particle, a cell, or dare we say it — an atom. He would do all of these things and more.
His signature means of getting around was making a prosaic phone call but then shrinking to an atomic size and riding the electron connection to the receiving end!
Here was a hero whose like had never been seen before! The Atom would go on to become a member of the Justice League though most of the time he was content to provide scientific support rather than go on field missions. He felt his power had a limited use and only participated in certain kinds of missions.
To be fair to the character, the Atom's molecular control made it possible for him to be the most dangerous member of the Justice League if you didn't mind the Atom manipulating atoms, molecules, cells, organs or simply expanding to his full size inside your body…as his enemy, Dwarfstar does with similar size control powers. Ugh.
Despite his minuscule size the Atom has enjoyed a long career since his debut, granted with doldrums where the character languished in limbo or in strange stories which are sometimes best forgotten. His adventures in Brazil for instance (from the Sword of the Atom series):
From Sword of the Atom Special #2 (1985)
And that’s how Ray Palmer became a jungle barbarian, a counter-espionage agent, a teenager, a concerned ex-husband, and a border guard of the multiverse (don't ask, retconned away…)
Even a hero as tiny as the Atom gets a crowning moment of awesome.
- In the alternate future story, "Rock of Ages", Darkseid has found the Anti-Life Equation and rules Earth, although he is killed when Connor Hawke and the Atom manage to bypass his protective force-field when Atom shrinks down to the size of a speck of light (reasoning that light must penetrate the force-field, otherwise Darkseid could not see) and detonates a bomb inside Darkseid's head.
Dr. Henry Pym: Scientist Supreme
Ant-Man is the name of several fictional characters appearing in books published byMarvel Comics. Ant-Man was originally the superhero persona of Hank Pym, a brilliant scientist who invented a substance that allowed him to change his size. Hank Pym was created by Stan Lee, Larry Lieber, and Jack Kirby and first appeared in Tales to Astonish#27 (Jan. 1962); his first appearance as Ant-Man was in Tales to Astonish #35 (Sept. 1962).
After Pym retired his Ant-Man identity, successors Scott Lang and Eric O'Grady have used Pym's technology to take on the role of Ant-Man.
Ant-Man may have made his first appearance in Tales to Astonish but he really didn't hit the big time until he became a charter member of the World's Mightiest Heroes, The Avengers. Yes, that's right, for all of you Marvel Cinematic Universe types, Ant-Man and his wife-to-be Janet Van Dyne (the Wasp) were founding members of the Avengers.
Yes, over there in the corner on the left surfing two ants is Ant-Man. And here-in would become the dilemma of the character over his long career.
You see, Ant-Man's powers were the ability to reduce himself in size using a molecular material he dubbed Pym Particles (no scientific ego problems, right?) These particles would let him change his size from a normal human to the size of a large ant. He did maintain his normal size strength and this could make him able to pack quite a punch.
Using a cybernetic helmet of his own design, he could also summon and control ants and they would follow his commands. He could use them as spies or as attackers. Most often he used them as flying transport.
However, in a group boasting its own superhumanly strong monster, a man in a suit of powered armor and a self-declared god, being able to shrink to the size of an ant had limited applications. This inferiority complex along with a growing psychosis due to his changing his size would eventually lead to him taking on a new identity: Giant Man. The Avengers roster would grow and Pym wanted to be considered a heavy hitter.
Pym would be the Avenger's go to scientist for his entire time in their roster, constantly fighting feelings of inferiority as the Avengers lineup grew more diverse and more powerful. While he loved his wife, it seemed their relationship grew more strained as his issues with being a heavy hitter became more problematic.
Hank would go on to create Ultron, the Avenger's greatest, nigh indestructible menace whose threat would resurface again and again over the decades.
Ultron never stopped improving himself though his greatest threat to the Avengers may have been when he was Ultron-5 and brought the Avengers to the brink. Pym was never able to forgive himself for creating Ultron. He would also change his name and costume to Goliath during this period. It didn't help his issues. If anything he became more violent and dangerous during battles.
Pym's instability would continue as he used his size-changing powers and would eventually be unable to change size. This would force him to take on a new identity: Yellowjacket. For Pym, this identity would herald a number of life-altering changes.
Determined to try to show the team he was worthy of being an Avenger, Hank was actually on trial and about to get kicked out for excessive force during a battle. The team was fighting a mysterious woman and Cap had convinced her to stop fighting. Hank came along and zapped her in the back. This could have caused her to re-ignite the fight and defeat the team. In an effort to prove to the team he was still worthy of being an Avenger, Pym concocted a plan to create a robot only he could stop (ala Syndrome from the Incredibles).
Hank sneaks off to his lab to create his super-robot and is discovered by Jan. What follows is the character's ultimate defining moment. He never recovers from this event socially, as an Avenger or as a character in the Marvel Universe.
One of the smartest men in the Marvel Universe with the social acumen of a angry child. In a rage, Hank strikes her, gaining an undeserved reputation as a wife-beater. They divorce soon after.
Hank's decent into madness continues until he realizes he isn't cut out to be a superhero and returns to his lab.
He takes on the identity of Dr. Pym, a science hero/adventurer who uses science to make the world a better place. Since he can no longer use his size changing powers on himself, he instead shrinks objects and tools and resizes them as he needs to.
His relationship with Jan improves during this time because he has for the first time accepted he is not defined by his superpowers. Pym develops as a character in a far different way than the Atom does. There is a whole lot of history we can't even cover.
Janet dies, Hank takes on a new identity in tribute to her, becoming the Wasp. Hank trains new Avengers, he creates a new mansion in a pocket dimension. You have years to catch up on what may be one of the most interesting and human characters in the Avenger's lineup.
Eventually, Pym too will have a moment of awesome as he discovers he is the Scientist Supreme.
The Pym Particles are a fundamental sub-atomic particle that allows Hank Pym to shrink down and pass into a sub-atomic realm called Underspace, and to grow to an abstract level called the Overspace.
Abstract entities like Eternity reside on other planes of existence such as Overspace. The exact polar opposite of that would be Underspace – a plane of reality that lies below the dimension called the Microverse. Underspace is the realm Henry Pym placed his headquarters, the Infinite Avengers Mansion, for his team of Avengers because he discovered his former teammate Thor sent Janet Van Dyne, the original Wasp, there. —Underspace entry on the Marvel Wikia
Pym has visited the abstract realm and met Eternity when he went into Overspace.
Never forget this, Hank Pym. You are my champion. You are my avenger! More than a founding Avenger of old, you are the founder of Avengers yet to come. A new Age of Heroes is upon us…more than any being, I put my trust in you. To you I entrust more than myself. To you I entrust the future. But for now, here is what you must do… — Eternity
When Henry Pym grew beyond the macroverse into Overspace, he met Eternity, who thanked him for saving reality from Chthon. He gave the title "Scientist Supreme" to Pym because of his desire to take science to the point of studying magic. He sent Pym back to Earth, telling him that he was the founder of the Avengers to come and promised a new age of Heroes was coming. —Eternity entry on the Marvel Wikia
Hank Pym is a genius, one of the founding members of the Avengers, the creator of Pym Particles and Ultron, a sufferer of Bipolar disorder and a modern-day superhero. He has acted under many memorable identities such as Ant-Man, Giant Man, Goliath, Yellowjacket, and the Wasp. He is also the Earth's Scientist Supreme, as decreed by Eternity.
Two shrinking heroes separated by a year and 50 years of creativity have ended up in very different places. One may have been a copy of the other but by no means were these two scientists merely standing in the shadows of giants or gods. They were both expressions of the human desire to expand their knowledge to the limits of their respective universes. Not bad for two guys whose power was just shrinking…
See Also: How does Ant-Man stack up against other Marvel heroes?