In recent internet slang (not sure if this was an existent term before its recent meme populatity), a "sigma male" is a dominant or highly successful male who does not conform to society's standards; he does his own thing. (As opposed to integrating to the top of a social structure.) You have the "gigachad" Alpha Male, your generic beta male, and then you have the sigma male, a lone wolf.

Oftentimes confused with the alpha male to those who do not possess a keen eye. The worst part is that there's plenty of 4chan incel degenerates (and I mean that) that consider themselves "sigma males", like, as a part of their identity. Just look at a few greentext memes and you'll know what I mean. Like, just three or four greentexts.

Short and sweet writeup because there's not much to cover. I'd like to node gigachad but I don't possess the intelligence, the power, to do so. Maybe someday.