The Noble Houses of Soul Society have an unclear role in the culture, social and governmental aspects of that dimensions existence. The Four Noble Families carry the most weight and appear to have some influence over the governmental institutions and even institutions outside of the government. The military have no authority to act against a noble family without evidence that their actions are treasonous to Soul Society.
Four Noble Families
By tradition, the head of the Shihōin family leads the Onmitsukidō. Also known as the Tenshiheisōban (House of Godly Gears), they are the Caretakers of the Hōgu ("Treasure Tool") and Bugu ("War Tool") said to have been bestowed on them by the gods.
Members of the Kuchiki family have been known to wear Kenseikan ("Star-Pulling Insert") in their hair, which symbolizes their nobility as one of Four Noble Families. The Kuchiki family also has a white scarf made by the master weaver, Tsujishirō Kuroemon III. The scarf is made from the Ginpaku Kazahana no Uzuginu (Silks of the Silverwhite Wildflower), a silver-white, windflower light silk, and is a family heirloom that is handed down from generation to generation and is given to each Kuchiki family head. The scarf alone is worth enough to buy ten mansions in the Seireitei. By tradition, the family has been charged with compiling and protecting the history of Soul Society. The family resides in the Kuchiki Family Manor.
Lower Noble Houses
Traditionally serves the Shihōin Clan by joining the Onmitsukidō. The Fēng Family (Fon-ke) makes its living as assassins and executioners. Any member who doesn't pass the test to get into the Onmitsukidō's Executive Militia is exiled.
The Kyōraku Family (Kyōraku-ke) is an old, prestigious and high-ranking noble family.
A low-class aristocratic family.
An aristocratic, rich family. The family has a history of service in the Onmitsukidō.
A lesser noble family.
Kasumiōji Clan & Kannogi Family
The Kasumiōji Clan is a high-ranking noble family that is just below the four great noble families in status, with Yoruichi Shihōin commenting that their circumstances are a bit "special." The Kasumiōji family members are well known as master forgers in the art of weapons crafting, making the finest weapons in all of Soul Society. The family is traditionally lead by a female.
The Kannogi Family is another high-ranking noble family. They are connected to and often affiliated with the Kasumiōji Family.
Former Noble Houses
The Shiba Clan: The family was once the fifth great noble family, having prestige along the lines of the Kuchiki and Shihōin families. For an unknown reason, the Shiba family fell from their high status position after the death of Lieutenant Kaien Shiba. The family specializes in fireworks.
While not exactly noble said families are notable for being highly respected and revered within Soul Society.
The Ise Clan (Ise-ke; lit. "Ise family") is a clan of Shinto Priests from Soul Society.