That "solo hero" is BJ motherfucking Blazkowicz. We're talkin' about a guy who can take out armies of Nazis, super soldiers, x-creatures, the undead, and monsters from the Veil. He spanked Hitler and danced around Heinrich I like it was a ballet.A specific form of Memetic Mutation when the fandom of a series exaggerates a character that is simply badass, or sometimes not all that impressive, to preposterously epic god-like levels. Despite the name, it doesn't necessarily have to be a widely known Internet meme, and is sometimes just an in-joke among the fan-base. In some cases, the writers agree. Often overlaps with Fan Wank. Fear too the Memetic Psychopath, and especially the Memetic Molester. In-universe, this can be the result of being Shrouded in Myth, or a God-Mode Sue if done poorly. Upgrading the badassery significantly with a character from a previous work is an Adaptational Badass. When done to a historical character, it's a Historical Badass Upgrade. Compare Memetic Sex God, Testosterone Poisoning. Contrast Memetic Loser.
BJ blocks bullets with his manly ass chin, and shakes off shrapnel like a dog after a bath. A Nazi general was once told by one of his officers that BJ Blazkowicz was coming, and his heart exploded from fear.
If a Nazi is constipated, then just say "BJ Blazkowicz" while he's on the toilet. For every Allied soldier and innocent civilian killed, BJ kills a hundred Nazis. BJ's idea of a vacation is a Nazi occupied war zone.
There's only one BJ Blazkowicz, and as long as he's breathing air, no Nazi is safe. BJ's not worried about how many there are, he's just worried about where the next box of ammo is.