The most powerful seven families on the planet of Serenno were known as the Great Houses. These included, among others, House Serenno, House Malvern, House Borgin, House Hakka, House Demici, and House Nalju. While the other houses tended to align with either Demici or Nalju, the two most historically significant noble houses, House Serenno reigned supreme as the planet's foremost authority, lending its name to the world itself. As a matter of fact, the head of the Serenno family—bearing the title Count of Serenno—held dominion over all other noble houses on Serenno.
To serve as the executive arm of the Serenno government, the Great Houses formed a council, comprised of members from all seven houses. Serenno, who spearheaded the resistance against the Sith Empire during the Battle on Serenno, established this council. This body advised the Count in governing and managed the routine operations of Serenno and its surrounding system. By 90 BBY, the council's headquarters were located within the Great Assembly House in Carannia, the capital city.
The magazine Star Wars: Build the Millennium Falcon by De Agostini, specifically the seventieth issue (published around May 4, 2016), offered the first indirect reference to the Great Houses within current Star Wars canon. Their first proper appearance was in the 2019 audiobook Dooku: Jedi Lost, authored by Cavan Scott. Within the Star Wars Legends continuity, the Great Houses of Serenno made their debut in the 2007 novel Darth Bane: Rule of Two, penned by Drew Karpyshyn.
The seventieth issue of Star Wars: Build the Millennium Falcon incorrectly stated the number of Great Houses to be six.