After listening to How to Defeat a Demon King in 10 Easy Steps (a total riff on Zelda) I was inspired by the highly colorful 'demon generals' employed by the Demon King and thus, this list was created. All of these individuals should be workable for powerful sub-bosses or even full on boss fights themselves.

Elziara, the Mistress of Death, was paramount in securing Emperor William's position. It was a shock when the woman who came to epitomize the power of the Imperial line would suddenly disappear when her husband would need her most.

Agdan is an urbane and polite dwarf of older years, and is known to be a master butcher, a procurer of carcasses

Beverly is a career troubleshooter, a type of shadowrunner who works in the gray zone

Scion of the Bancroft-Ashpool bank and holding hypercorp, Ermingarde holds the position of being possibly the most powerful woman in the Solar System

For every Firestarter, Professor X, and Eleven, there are a dozen modestly useful parapsychic powers, and at least one or two completely useless parapsychics

An ordinary man catapulted into extraordinary circumstances, in the worst possible way.

Character profile for a flawed leader

24/30 craftsmen for your reading pleasures

ION is a towering and intimidating person, part of the CANNONBALL crew of shadowrunners

Dossier file of Aengoth Elmlock, the self-flagellating warrior. Some stuff taken from the people on /tg/. Visit 1d4chan for more info.

Also known as the Murderer of Mothers, the Matricidor, and the Hell Childe

Dossier file on Francis the Nerdy Minotaur, expert on everything to do with mazes and labyrinths. Need to know something? Ask him.

Dossier File on a young Nord child called Toralf Young-Sword. (Some of the things in this post are taken from Skyrim because I suck at naming stuff.)

The female protagonist of the Chinese fantasy novel series I'm writing. 

A heavily scarred deep gnome wizard with the most grimdark backstory I could conceive.
A monster hunter. Definitely not a hero, though he is capable of being heroic.
Too many rainbows and butterflies in your story? Throw this little fella in the mix.

unicorn

The Huntsman Summon is a nature/survival summon spell that is relatively easy to reach and learn, and of high utility to those who will spend a large amount of time in nature and surviving on their wits and what they can hunt. The Huntsman can also fight, if needed.

Also known as buzzboys and drone troopers

A highly eccentric socialite and techno-criminal kingpin in the Cosmic Era, suitable adversary for low level heroes, or a patron for low level villainous henchmen