A Golden Bull or chrysobull was a golden ornament representing a seal (a bulla aurea or "golden seal" in Latin), attached to a decree issued by Byzantine Emperors and later by monarchs in Europe during the Middle Ages and Renaissance. The term was originally coined for the golden seal itself but came to be applied to the entire decree. Such decrees were known as golden bulls in western Europe and chrysobullos logos, or chrysobulls, in the Byzantine Empire (χρυσός, chrysos, being Greek for gold).

For nearly eight hundred years, they were issued unilaterally, without obligations on the part of the other party or parties. However, this eventually proved disadvantageous as the Byzantines sought to restrain the efforts of foreign powers to undermine the empire. During the 12th century, the Byzantines began to insert into golden bulls sworn statements of the obligations of their negotiating partners.^{[citation needed]}

Other European monarchs adopted golden bulls in imitation of the Byzantines, but used them much more sparingly. The exceptional nature of non-Byzantine golden bulls gave them a much higher profile than either the Byzantine originals or ordinary proclamations^{[citation needed]}. Notable golden bulls included: