Throne of Salt did this last summer: http://throneofsalt.blogspot.com/2018/06/20-soulslike-bosses.html, if you haven’t already check it out, it’s cool.
Here’s my crack at a similar thing:
1. Hungry Yvain
They locked away every witch accused to stand trial, together in blasphemy. When the day came, they opened the gaol to find only her, swollen to fill the entire basement.
2. Seventh Prince Areli
Their line was old, and sickly with consanguinity.
“I know of certain treatments,” the king’s physician whispered, “they are dangerous, but... you have many heirs”.
3. Palamon the Sophist
The wise men of the city knew they had a problem when he shouted down a thunderstorm. They learned that problem was beyond their ability to solve when he reasoned out the poison they had administered.
“We are inseparable” proclaimed the puppet to her fellow.
“For you hold my strings, and I hold yours” he replied.
5. Oathbreaker Engrand
“I will defend this place and keeps its secrets from those who would abuse them, until my final breath” Engrand lied.
6. Gluttonous Serpent
It would have eaten the fruit itself if it had been in Eden. See those arms pressing out from its belly, stretching the skin like gloves? Stay out of their reach. All that it swallows becomes its own.
7. The Lord Immured
“This is all wrong,” the lord cried as his dead servants held him fast, “YOU were meant to be buried with ME!”
8. Fading Phalanx
Could a fantasy hurt you, stab you, bleed you? They will try to convince you that one could not, as that is the foundation of their tenuous reality.
9. Archon Wreckage
It is said that the archons constructed this false world of matter to obscure the truth of God from mortal souls. Not so. God was the invader of this realm, bringing salvation and ruination alike.
10. Cemetery Chimera
The bodies piled up faster than they could be buried, faster even than the scavenging beasts, and the carrion birds, and the worms could eat them. The fleshworkers offered a solution, but as with all their children it grew to be more of a problem than the one it was born to solve.
11. Nithing Nag
They could not find a priest willing to banish the curse laid upon them, nor the beast that stalked with it, for the hatred necessary to call down such a thing must have been monumental, and deserved.
12. Paradoxical Revenant
True undeath is impossible. Something is either living or not, there is no in-between, no inversion. There are approximations, crude workarounds, and then there are those that exist despite their own impossibility. Reality shudders at their passing.
13. Dogs of Count Arnau
These were the hounds the dreaded count brought with him when he hunted intractable serfs. They gained a taste for human flesh, and found no difference in the meats of peasant and patrician.
14. Ratcatcher King
The rats here are clever, and have the souls of artists. See how elegantly, how inextricably they’ve woven together the pelvises, the feet of those who thought them vermin, fit only for eradication.
15. Extinguished Shayatin
“We will not bow before this animal, for he was spawned from chance and mud, while we were sculpted from flame by your hand alone” they wept, dousing their smokeless fire in bitter tears.
16. Charioteer Ben-Yeqon
He outraced the Flood on iron wheels, crushed armies beneath rims wider than an ox from horn to tail. He owes much to the blessings of his grandmother, not Eve, but Lilith.
17. The Snowmelt Troop
Hear and fear the crisp chiming of their icicle-bells at the beginning of the thaw. White hair, white skin, white cloaks, white bone spears to be stained red by slaughter. They range from the Court of Winter as one last reminder of the ferocity of their season.
18. Soulless Metharme
She is fascinated endlessly by that which she lacks, probing, cataloguing, dissecting until she understands it as completely as its maker. What is its mass? What moment does a person acquire it? What is the mechanism by which it interacts with the body? All this meat is only getting in the way of further investigation.
19. Unfortunate Menagerie
The emperor had a great fondness for all the creatures he read about in the bestiaries in his youth, and most of all for those with the faces of men: the manticore, the lampago, the sphinx. Alas, it was these he could never manage to acquire, by the guile of his scholars or the strength of his warriors. At last, he bade his tailors to stitch his scholars and his warriors within the skins of beasts, that they might complete his collection regardless of their failure.
20. Bloody Mary, the Queen Contrary
Bloody, from the many wounds she has suffered. Bloody, from the rivers she has spilled at swordpoint. At last returned from glorious conquest on the other side of mirrors, only to find a world that has forgotten everything but her name.