According to the internet culture database Know Your Meme, online males from this supposed class are usually considered equal to alphas on the dominance hierarchy but exist outside of the structure by choice. John Wick has often been cited as a prominent example of a sigma male.

The term itself has been attributed to writer Vox Day, aka Theodore Robert Beale, a self-described Christian nationalist. On his blog, he often shares detailed explanations of the hierarchy of males using the Greek alphabet.

On May 16th, 2010, he published, "Explaining sigma. Again," in which he wrote that the sigma is not just a social outcast, but a person who despite being a supposed social outcast "wins" at the social game.

"[Sigmas are] the outsiders who don't play the social game and manage to win at it anyhow," he wrote. "The alphas hate sigmas because they are the only men who don't accept or at least acknowledge their social dominance. (NB: Alphas absolutely hate to be laughed at and a sigma can enrage an alpha by simply smiling at him.)"

"Everyone else is vaguely confused by them. At the party, it's the guy who stops by to say hello to a few friends accompanied by a tier-one girl that no one has ever seen before. Sigmas often like women, but also tend to be contemptuous of them."

He has also listed some pop culture characters as examples, including Han Solo, Neo, and many Clint Eastwood roles.

Over the course of the 2010s, explanations of the sigma male began growing more popular online. But it has received a fair share of criticism, too.

Writing for the Daily Dot, Gavia Baker-Whitelaw said that, "Conveniently, [the sigma male concept] offers men the chance to rebrand themselves as a cool, sexy loner if they've alienated their friends and loved ones by ascribing to self-defeating theories about gender and relationships."

"Once again, the men's rights community has come so close to realizing that their real problem is the restrictive nature of old-fashioned gender roles. 'Redefining masculinity' can be a helpful idea for many people, but if you're redefining it as a hierarchy of tough wolf guys versus incels, it's probably time to go back to the drawing board," Baker-Whitelaw added.

Dr. Leonor Gonçalves, who is a Research Associate in Neuroscience, Physiology, and Pharmacology at the University College London, would probably agree with Baker-Whitelaw.

"We can wish to hold on to the past and choose to emulate the societal structure of ancient animals," she wrote. "But the fact [some animals] have survived for so long without changing is a reflection of how well they are adapted to their environment – and how little this has changed."

"Human ancestors have left the ocean, developed lungs, vocal cords and many things in between. We have explored continents, built flying machines and some of us even live outside the Earth. We crave change and challenge. We also try to make our societies more fair and balanced and aspire to make humanity better and more advanced," Gonçalves continued.

"What's more, the animal kingdom is full of examples of hierarchies, with the highest level of organization observed in insects ... In the world of bees, the queen is much larger than the males and the only fertile female. She lays all the eggs in the colony after being fertilized by several males. After [the] breeding season, the males are driven out of the colony and die. If we chose to organize society in this 'natural' way, would we be okay with that?" she wondered.

But while categorizing men as a pack of wolves and labeling them with Greek symbols might be archaic (or even dumb), the beauty of such loose definitions is that you can bend them in whatever way you want — there's no academic institution safeguarding it. And judging by its content, the Twitter account 'Sigma Male Activity' is painting a pretty inspiring picture of sigmas.