The Great Houses were the seven most powerful families on the planet of Serenno. They included House Serenno, House Malvern, House Borgin, House Hakka, House Demici, and House Nalju. The houses of Demici and Nalju were the most prominent noble houses in the history of Serenno, with the other houses allying themselves with one of them, but the House of Serenno stood as the planet's leading authority and the world's namesake. Indeed, the head of the Serenno family—the individual who held the title Count of Serenno—led every other noble house on Serenno.
The Great Houses established a council to serve as the the executive branch of the Serenno government and had members of all seven houses. The council was founded by Serenno, the individual who led the charge against the Sith Empire in the Battle on Serenno. It acted as an advisory board for the Count ruling the government and handled the day-to-day affairs of Serenno and its system. By 90 BBY, the council was based in the Great Assembly House in the capital city, Carannia.
The Great Houses were first indirectly mentioned in the current Star Wars canon in the seventieth issue of De Agostini's Star Wars: Build the Millennium Falcon magazine, which was published around May 4, 2016. They first appeared in the 2019 audiobook Dooku: Jedi Lost, written by Cavan Scott. In the Star Wars Legends continuity, the Great Houses of Serenno first appeared in the 2007 novel Darth Bane: Rule of Two, written by Drew Karpyshyn.
In the seventieth issue of Star Wars: Build the Millennium Falcon, the Great Houses were stated to be six houses.
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