The Iron Islands is one of the nine constituent regions of Westeros. They are a cluster of seven small, rocky islands off the western coast of the continent, in  Ironman's Bay. The Iron Islands are ruled from the castle of Pyke by House Greyjoy. The islands are the smallest and one of the least-populous regions of Westeros, but the naval skills of their people, the Ironborn, are unmatched and they enjoy great mobility due to their ships. The Ironborn also have a unique culture and religion, centered on maritime raiding and pillaging other peoples, that sets them apart from mainland Westeros. However, they were forced to stop these practices following the Targaryen Conquest, or at least to stop raiding around Westeros itself. Although this edict was not always effectively enforced by the Iron Throne,  Daenerys Targaryen reinstated it as a condition of the Iron Islands regaining independent rule nearly 300 years later.

Prior to the Targaryen Conquest, the Iron Islands were a sovereign kingdom, along with the other "Seven Kingdoms" of Westeros. For the three generations immediately preceding the Conquest, the ironborn also controlled the Riverlands, which they had in turn conquered from the Stormlands. Following the Sack of King’s Landing and death of Daenerys, a newly-formed council, including the Iron Islands’ Yara Greyjoy, elected Bran Stark as the new King of the Six Kingdoms, with the North reclaiming independence. Bastards born in the Iron Islands are given the surname Pyke.

The Iron Islands are located off the western coast of Westeros, in Ironman's Bay (an inlet of the Sunset Sea). They are north of the Westerlands, west of the Riverlands, and southwest of the Neck and the North. However, the entire western coast of the continent, from the Wall in the North to the Arbor in the extreme south of the Reach, are considered to be within range of far-reaching ironborn coastal raids. Centuries before the Targaryen Conquest, the Iron Islands did indeed rule much of the coast from the Arbor to Bear Island in the North, and at the time of the Targaryen Conquest, they ruled the Riverlands.

The Iron Islands are small and rocky, swept by fierce storm winds, with poor soil and hardly any natural resources. The few poor crop fields that are present have their rocky soil plowed by thralls, men captured in raids and forced into servitude; even the noble houses of the islands usually cannot afford draft animals, and the Old Way discourages the ironborn themselves from farming, anyway. While located at roughly the same latitude as the Eyrie in the Vale or the Twins in the Riverlands, the harsh storm winds that howl through the islands make them fairly cold. In such precarious circumstances, the inhabitants came to rely heavily on the bounty of the sea, and ultimately raiding the mainland.

Notable places shown in the series are: