Noble house

The Seven Kingdoms of Westeros are divided between many hundreds of noble houses of various sizes. In Westeros ultimate power derives from the King on the Iron Throne and descends through the Great Houses that rule the constituent regions of the continent to their vassals.

There are ten Great Houses, and each of them have a number of vassal houses (sometimes also referred to as lesser houses) in their liege. The most powerful vassal houses may themselves field armies of a few thousand and control large regions, while the smallest houses may be little more than impoverished landholders with only a few men to their name. Members of the nobility are called "highborn", in contrast to lowborn commoners.

Some of the most powerful noble Houses rival the smaller Great Houses in terms of wealth and the size of the armies they can field, e.g. House Harrigon rules Smithestone, a massive fortress, and possesses large armies and fleets of its own. Other noble Houses, while technically holding this rank, are relatively poor.

A typical noble house is seated at a castle and controls the land around it, collecting tithes and taxes from farmers, lesser landholders and smallfolk. In times of war they are expected to recruit and maintain a number of soldiers for their lieges. In most of Westeros only men can become ruling lords, and women can only rule if the rest of the male line has been extinguished or if they are acting as regents for their sons until they become of majority.

In Dorne men and women have equal property, inheritance and ruling rights.

Chiefs

Some noble houses hold enough power and enough wealth, that they are considered to be Great Houses, but do not have the position due to them lacking control over a constituent region. (e.g. The North). These powerful houses are called "chief noble houses" and stand above the regular noble houses, but below the sovereign Great Houses. Chief noble houses usually have more than one vassal. A chief is not an official position, but is used to compare the "lesser noble houses" from the more powerful ones.

Some notable chief houses are:

• House Tarly
• House Redwyne
• House Bolton (pre-Red Wedding)
• House Frey (pre-Red Wedding)
• House Dragen
• House Montrose (pre-Day of Daggers)
• House Royce
• House Harrigon (pre-Stormmoot)
• House Reed
• House Harlaw
• House Bergen
• House Grayburn
• House Mercer
• House Mallory
• House Oakenshield

Physical traits

Some of the noble Houses have a marked propensity for physical traits which are passed down through the generations. They do not have a concept of "genetics" as such, but sometimes understand that "the seed is strong" and that black hair tends to be a dominant trait over blonde hair. Some of the notable examples include:

• House Blackgard - very large size, frequently over six feet tall and well-built, classic "Borderman features" of long black hair and beards, muscular body and minor Durrandon/Baratheon features. Recent generations of Blackgards tend to look slightly like the Starks in terms of appearance.
• House Baratheon - black hair, blue eyes, and square jaws
• House Bolton - Black hair and eerie "ghost grey" eyes (somewhere between very pale blue and practically like dirty ice)
• House Dragen - Straight black hair and maroon-red eyes
• House Florent -  large ears
• House Harrigon - Dark hair, blue eyes and minor Orosian/Valyrian features.
• House Lannister - curly blonde hair and green eyes
  • House Lannister of Lannisport -  straight blonde hair and green eyes
• House Martell - classic "Salty Dornish" features of olive skin, dark hair, and dark eyes.
• House Nyte - pitch black hair and extremely light blue eyes, said to look like "an azure sky of deepest summer" or "eyes like sapphire"
• House Redwyne -  red hair
• House Rylen - Brown, "nearly blood red" eyes.
• House Stark - Black hair and grey eyes
• House Targaryen - classic Valyrian features of pale skin, white (platinum-blonde) hair, and purple eyes (changed to simply brightly colored, i.e. blue eyes in the TV series)
• House Tully -  auburn hair and blue eyes

It hasn't been said that there is a "traditional" House Greyjoy look, but most in the current generation tend to have dark hair. So few living members of House Arryn have appeared in the narrative that it isn't clear what a "typical" Arryn looks like. Sweetrobin is half-Tully and thus might not be a good indication. Both Sweetrobin and his cousin Harold have blue eyes, as well as brown hair; though they are said to be among the purest Andal bloodlines, and Andals often have lighter hair.