Galician /ɡəˈlɪʃən/ (galego IPA: [ɡaˈleɣo]) is a language of the Western Ibero-Romance branch, spoken in Galicia, an autonomous community located in northwestern Spain, where it is co-official with Castilian, as well as in border zones of the neighbouring territories of Asturias and Castile and León.

Modern Galician and its southern sibling, Portuguese, originated from a common mediaeval ancestor called variously by modern linguists as Galician-Portuguese or Mediaeval Galician or Old Galician or Old Portuguese. This common ancestral stage developed in the territories of the old Kingdom of Galicia, which covered the territories of modern day Galicia and northern Portugal. In the 13th century it became a written and cultivated language. In the past Galician and Portuguese formed a dialect continuum. For many scholars this continuum still exists today at the level of rural dialects. Others point out that modern Galician and Portuguese have diverged notably during the past seven centuries.

Historically, the Galician-Portuguese language originated from Vulgar Latin as a Western Romance language in the lands now in Galicia, Asturias and northern Portugal, which belonged to the mediaeval Kingdom of Galicia, itself comprising approximately the former Roman territory of Gallaecia as modified during the two centuries of the Suevic Kingdom of Galicia. The standards of the language began to diverge in the 14th century, as Portuguese became the official language of the independent kingdom of Portugal and its chancellery, whilst Galician was the language of the scriptoria of the lawyers, noblemen and churchmen of the Kingdom of Galicia, then integrated in the crown of Castile and open to influence from Castilian language, culture, and politics. During the 16th century the Galician language stopped being used in legal documentation, becoming de facto an oral language, with just some use in lyric, theatre and private letters.