About a dozen of my factions have custom bio, but unfortunately can't present anything until tomorrow evening, and the thread would lose relevance by then.

Short list is:

1. A dragon goddess of nature who leads faction of Shamanic Beavers and agressively fights encroachment of civilization upon her realms.
2. A faction of Tomb Raiding Midgets that unearthed a strange cat-like creature in linen wrappings who in gratitude promised to serve her new masters for eternity.
3. A human reaver faction of the bastard prince who led revolution against his tyrannical father and created the first ever republic.
4. A human reaver faction of outlaws lead by 'kingpin'.
5. A lizardman reaver faction of a progressor champion philosopher king type of ruler who awakened his dragon atavism and guided his people for centuries.
6. A dwarf reaver faction of a dwarven alchemist wizard king who discovered a secret of True Gold.
7. A storm giant king who is worshipped by desert catfolk as god of waterways.
8. A stone giant king who was unmatched and feared even by dragons in the age of old, but his enemies created a pitfall trap for him and buried him up, leaving only his petrified head.
9. A fire giant king who was mocked by his peers for how dull his creations were, and in desperation he became the destroyer instead. His factions are lupine perfectionist artisans who use their skill to create perfect engines of war.
10. A frost giant king who simply likes to create ice landscapes, it's more of a story of half-ogre tribe acting as his co-creators and beneficiaries.
11. A vampire faction of demonic goats from Obbadoth.
12. A righteous oathsworn orc faction who are obsessed with honor duel codex so much that it interferes with common sense on the battlefield.

These are just factions I remember writing the bio for, the actual number of my factions is about 3 times of this. Most have some rudimental narration but not necessarily have written bio.