The Isabelline style, also called the Isabelline Gothic (Spanish: Gótico Isabelino), or Castilian late Gothic, was the dominant architectural style of the Crown of Castile during the reign of the Catholic Monarchs, Queen Isabella I of Castile and King Ferdinand II of Aragon in the late-15th century to early-16th century. The Frenchman Émile Bertaux named the style after Queen Isabella.

It represents the transition between late Gothic and early Renaissance architecture, with original features and decorative influences of the Castilian tradition, the Flemish, the Mudéjar, and to a much lesser extent, Italian architecture. The consideration or not of the Isabelline as a Gothic or Renaissance style, or as an Eclectic style, or as a phase within a greater Plateresque generic, is a question debated by historians of art and unresolved.