Breogán (also spelled Breoghan, Bregon, or Breachdan) is a character in the Lebor Gabála Érenn, a medieval Christian history of Ireland and the Irish (or Gaels). He is believed to be the son of Brath and is described as an ancestor of the Gaels. The Lebor Gabála claims to explain how the Gaels are traced back to Adam through the sons of Noah and how they arrived in Ireland.

The story says the Gaels spent 440 years traveling across the Earth and faced many difficult experiences. Eventually, they sailed to Iberia and conquered it. There, a leader named Breogán built a city called Brigantia and constructed a tall tower. From the top of the tower, his son Íth saw Ireland. Later, some of Breogán’s sons, along with other Gaels, sailed to Ireland. They agreed to divide the land with the Tuatha Dé Danann, the Irish pagan gods, who took control of the Otherworld.

Brigantia is likely referring to A Coruña in modern-day Galicia. Breogán’s tower may be based on the Tower of Hercules (built by the Romans in A Coruña) or the Tower of Babel. The idea that the Irish Gaels came from the Iberian Peninsula may be linked to the similarity of names like Iberia and Hibernia, and Galicia and Gael. Medieval historians sometimes made similar claims about other nations based on their names. A story about a monk who saw a mysterious island from the top of the tower of Brigantia was written in the early 1000s in Galicia. This story, recorded in two 14th-century manuscripts, is called Trezenzonii de Solistitionis Insula Magna ("Trezenzonius’ Great Island of the Solstice").

Breogán’s son was Bile, who became the father of Milesius (also called Míl Espáine, meaning "soldier of Hispania or Spain"). Milesius is said to be the ancestor of the Irish people. While this is generally considered a myth, a 2006 genetic study at Oxford University found that most people in the British Isles are descended from Neolithic farmers who lived in coastal northern Spain.

The Lebor Gabála was a widely read and influential book. Galicia is sometimes called the "Home" or "Nation" of Breogán (in Galician, fogar or nazón de Breogán). This description appears in the anthem of Galicia, Os Pinos. A large statue of Breogán stands near the Tower of Hercules in Coruña. The professional basketball team in Lugo, Spain, is named CB Breogán in his honor. In Madrid, Spain, there is a park called Parque de Breogán, named after this legendary figure.

Sons

Breogán had nine other sons in addition to Bile, who was the father of Milesius. Among these sons, Íoth arrived in Ireland first but was killed by the sons of Cermait, which led his family to come to Ireland for revenge. Íoth's son, Lughaidh, is remembered in the place name Corca Luighe. Íoth's brothers are also associated with other place names: Breogha, Cuailgne, Muirtheimhne, and Cualu in the territories of their descendant peoples; Fuad, Bladh, and Eibhle in mountains (Sliabh Fuaid in the Fews, Slieve Bloom, and Slieve Felim respectively); and Nár in "Ros Náir" in Slieve Bloom and "Cathair Náir" in Slieve Mish. Through Bile, Breogán is considered the 46th great-grandfather of Conn Cétchathach, making him an ancestor of the Connachta according to the legends.