Cadet branch

A cadet branch is a noble house that descends from another noble house. These are usually born when a member of a noble house, who doesn't stand as heir of the family seat, is granted lands and titles of his own. Noble houses can also be considered cade braches if they can prove descent from a daughter of a more ancient noble house.

Bastards or trueborn descendants of bastards, when granted lands and titles of their own, also found cadet branches.

Known cadet branches (male line)
House Baratheon of King's Landing. Founded by Robert Baratheon after taking King's Landing at the end of the War of the Usurper. It is actually a cadet branch of House Lannister as Robert's trueborn children were actually fathered by Ser Jaime Lannister, the Queen's brother.
 * House Karstark of Karhold, formerly House Stark of Karl's Hold. Founded by Karlon Stark, a younger son of House Stark of Winterfell.
 * House Lannister of Lannisport. Descended from the Lannisters of Casterly Rock.
 * House Florent. Descended from a scion of House Gardener.
 * House Baratheon of Storm's End. Founded by Orys Baratheon, a bastard son of Aegon Targaryen's father.
 * House Baratheon of Dragonstone. Founded by Stannis Baratheon when he's made Lord of Dragonstone after Robert's Rebellion.

Known cadet branches (female line)

 * House Tyrell, cadet branch of House Gardener through the female line.
 * House Baratheon, descendants of House Durrendon, whose last member, Argalia Durrendon married Orys Baratheon.
 * House Lannister, boasting descend through the female bloodline to Lann the Clever.