Zack Snyder's Justice League: Who is Ryan Choi and what are his powers?

The vaunted Zack Snyder's Justice League is now streaming on HBO Max, and whether the long-awaited four-hour epic lives up to expectations or not, one thing it certainly delivers on is a new depth of DC lore including plotlines, concepts, and even characters from comic books.

On that last note – among appearances from New Gods and even Martian Manhunter – there's a slightly less well-known DC comic book character hiding in the film, one whose legacy may actually be somewhat familiar to certain viewers.

Spoilers ahead for Justice League: The Snyder Cut

We're talking about Ryan Choi, who appears in Justice League: The Snyder Cut as a STAR Labs scientist played by actor Zheng Kai, working alongside Cyborg's father, Silas Stone. Though he doesn't seem to have a superhero secret identity in Snyder's DCU just yet, in one key scene Choi hints at his alter ego from comic books, explaining his scientific specialty as "nanotechnology."

That's a crucial Easter egg, as in comic books Ryan Choi is the third character (and second size-changer) to take on the mantle of the Atom, the sub-atomic superhero who some viewers may know in a slightly different incarnation from CW's DC shows.

It remains to be seen whether any new elements from Justice League: The Snyder Cut will carry on into other DC films. But Zheng Kai's scenes as Choi were reportedly shot during the film's original production, which means that plans to bring Ryan Choi into later films could still be in the works.

But who exactly is Ryan Choi, and how does he fit into the legacy of the Atom, a DC mantle that goes all the way back to the Golden Age of the '30s and '40s? We'll get into it all right now.

Who is Ryan Choi and what are his powers?

Ryan Choi is the third DC hero to use the mantle of the Atom. The first Atom, Al Pratt, debuted in 1940's All-American Comics #19 (the same issue that debuted the original Green Lantern, Alan Scott). 

Rather than possessing the shrinking powers of his successors (we'll get into it), Pratt was a 5'1" weakling who trained his body to become an incredible powerhouse of muscle and fighting skill. His short stature combined with his bodybuilding prowess earned him the name "the Atom" (a tiny particle with great power) and a spot on the Justice Society of America.

In the late '50s and early '60s, DC (then called National Publications) began reviving some of its Golden Age heroes, kicking off the Silver Age of comics. This included reviving the name the Atom with a totally new concept in 1961's Showcase #34.

The Silver Age Atom was Ray Palmer, a super scientist working out of the fictional Ivy University who had mastered the art of shrinking himself and other objects to subatomic size using a belt built with material from a white dwarf star. Palmer became a longtime member of the Justice League, and was adapted to TV in CW's DC shows, played by Brandon Routh.

In 2006, DC revamped a significant portion of its line following the Infinite Crisis and 52 events, which revived the DC Multiverse. (The Multiverse itself has undergone many changes since, culminating in the recent Omniverse concept of the current 'Infinite Frontier' era).

Much like in 1961 when Ray Palmer was introduced, DC passed the mantle of the Atom to a new hero, this time with a direct connection to his predecessor.

The third Atom, who inherited Ray Palmer's shrinking belt and his position at Ivy University along with his superhero identity, was Ryan Choi, created by Gail Simone in the one-shot DC: Brave New World, which introduced a host of new characters and status quos for existing ones.

The one-shot established Ryan Choi as a brilliant young scientist from Hong Kong who had corresponded with Ray Palmer, and who took over his Ivy University professorship when Palmer went missing. Choi took on the mantle and powers of the Atom, including shrinking his body to subatomic size while also increasing his strength, growing to massive proportions, and shrinking and growing other people and objects along with him (not to mention Choi's innate genius intellect and ingenuity).

As the Atom, Choi found and rescued Ray Palmer from the Multiverse, with the pair going on to work together, sharing the codename and powers of the Atom (much in the same way Barry Allen and Wally West have been the Flash at the same time. There are plenty of DC examples).

Unfortunately, in a storyline that was contentious among both fans and critics, Ryan Choi was killed off at the hands of his enemy Dwarfstar, leaving him deceased even when the same story, Brightest Day, brought numerous other heroes back to life at its conclusion.

How does Ryan Choi fit into the current DC Universe?

When DC rebooted its continuity into the 'New 52,' Ryan Choi was introduced as a STAR Labs employee who helped Silas Stone turn his mortally injured son Victor into the hero Cyborg (a beat lifted almost directly into Justice League: The Snyder Cut). Unfortunately for Choi's fans, he never burgeoned into a superhero in this era, though the story Convergence kind of established that the pre-'New 52' Ryan Choi had actually survived in a subatomic state, giving him some slight vindication.

Then, when DC revised its continuity again in 2016's DC Universe: Rebirth one-shot, Ryan Choi was re-established as an Ivy University grad student working with Ray Palmer, who, as in Choi's first origin story, had mysteriously vanished.

Choi became the Atom again, joining the roster of a new Justice League of America title, in which the hunt for Ray Palmer became a central plot point. When the JLA did inevitably rescue Palmer, he passed the mantle on to Ryan Choi once again. Palmer has since continued to operate as the Atom as well – though both characters have only had supporting roles in recent years.

Prior to being adapted into Justice League: The Snyder Cut, a version of Ryan Choi appeared in CW's 'Crisis On Infinite Earths' TV event, played by actor Osric Chau. In CW's DC Universe, Ray Palmer is the founder of STAR Labs, and once again a brilliant (if somewhat socially awkward) scientist, however his powers generally focus around a suit of power armor, with his shrinking abilities only appearing onscreen a few years into his time on TV.

Choi appears in three episodes of 'Crisis On Infinite Earths,' which also marked the end of Brandon Routh's tenure as Ray Palmer (at least for ongoing appearances).

Also, fans who are gamers may recognize Ryan Choi as a DLC character from the DC fighting game Injustice 2.

Now, of course, Choi has made the jump to film with Justice League: The Snyder Cut. And though just a minor role, the film does lay the groundwork for Choi to become the Atom, should Warner Bros. choose to continue aspects of the Snyder Cut's still somewhat nebulous continuity.

The Atom is a legacy character in the DC Universe, with several incarnations having appeared in some of the best Justice League stories of all time.