One Fun Minor House From Each Region:
Stormlands - Toyne
First mentioned with Terrence Toyne, the paramour to Aegon the 4ths Mistress Betha Braken (namesake for Betha’s teats). Was cut to pieces in front of Betha for this. Terrences brothers attempted to avenge him though they were foiled by Aemond the Dragonknight. House appears to have gone outlaw after this, with the Smiling Knight Simon Toyne being leader of the Kingswood Brotherhood, and Myles Toyne the Captain General if the Golden Company (and possible lover to Jon Connington).
North - Forrester
Originally invented for the GoT Telltale game, only to be added by GRRM in ADWD. Appear to be a minor house sworn to House Glover and based in the Wolfs Wood.
Crownlands - Crabb
House of the GOAT Nimble Dick Crabb! Despite their seat, the Whispers, having been alledged by Dick Crabb to have been a ruin for 1000 years, they appear to at least still be landed Knights with multiple appearing on the Kingsguard, most notably Clement Crabb. Considerd half wild in the lore book, they are interestingly, as stated again by Dick Crabb to not be a cadet house but rather loyal directly to House Targaryen, having sworn themselves to Visenya during the conquest.
Westerlands - Kennings of Kayce
Despite being in the Westerlands are actually descended from the Ironborn Warrior Herrock Henning of Harlaw, who took Kayce with the help of the cities whores. There seems to be some indication that they were orginally landed Knights before being given Lordship follwing the Dance of the Dragons.
Iron Islands - Volmark
Were briefly Kings of the Iron Islands in 2ac following the destruction of House Hoare at Harrenhall. Were subsequently defeated by Aegon the 1st though there was a conspiracy to renstate them as Kings of the Iron Islands early on in the Targaryen era.
Aerion Damphair states outright that after the Greyjoys House Volmark has the greatest claim on the Iron Islands, being descended from the Black Line of House Hoare. Despite this they surport Victarian at the Kingsmoot. Euron Greyjoy later gives them the Shields as their Lordship, stating outright this is to cut into Victarian’s base of surport.
Riverlands - Vances
The Vances of Wayfarers and Atranta are 2 vadet branches of the older extinct Vance line. All three appear to have been established from the Andal Conqueror Armistead Vance who is said to have been the mightiest if ALL the Andal Conquerors, defeating the King of Hills and Rivers Tristifer iv Mudd.
The 2 Houses took oposing sides during the Dance of the Dragons, and to this day quarter their Coat of Arms with a green or black dragon.
Interestingly thier sigil is the same as House Flint of Widows watch, though this may just be a coincidence.
The Reach - Oakheart
Interestingly appear to be the Reach equivilant of a Marcher House. Their history is defined like the Dornish Marchers as a warrior culture standing against the Dornish. Infamously Alys Oakheart and her handmaidens were kidnapped by Wyl of Wyl and sold into Myrish Slavery. They later suggested forcing Princess Martell of Dorne to serve in one of the Kingland Brothels to Aegon the 1st.
Are stated outright to be one of the many Houses of the Reach to have a better claim on Highgarden than House Tyrell, and married extensively with their former overlords the Gardeners as well as House Peake.
Arys Oakheart, the POV everyone forgets, is from this house.
Dorne - Wyl
Basically the Dornish House that is so evil it justifies the existence of the Marcher Houses. Firstman in origin and one of the oldest in Dorne they were started by the warriormaid Wylla of Wyl. Aided and abeted the Vulture King during his rain of terror early in Aegon the first’s reign. Commited the aforementioned unspeakable acts against House Oakheart. Later kidnapped and killed Daeron Targaryen under a peace banner and imprissoned Aemond the Dragonknight, whom King Baelor the Good retrieved. Seemed to somehow survived unscathed until ADWD despite all this
Interestingly their name “the Wyl of Wyl” mirrors the naming conventions of the Northern Mountain Clans and Wildlings.