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.
Notable golden bulls included:
- The Golden Bull of 1082, issued by Alexios I Komnenos, granted the merchants of Venice free trading rights, exempt from tax, throughout the Byzantine Empire in return for their defense of the Adriatic Sea against the Normans
- The Golden Bull of 1213, issued by the papacy in recognition of its agreement with John Lackland in England.
- The Golden Bull of 1214, issued by Frederick II, Holy Roman Emperor ceding all German territories north of the rivers Elbe and Elde to King Valdemar the Victorious of Denmark.
- The Golden Bull of Berne, supposedly also issued by Frederick II in 1218, but now considered a forgery.
- The Golden Bull of 1222, issued by King Andrew II of Hungary. This confirmed the rights of the nobility; it was forced on him much in the same way that King John of England was made to sign the Magna Carta.
- The Golden Bull of 1224 (the Goldener Freibrief) was also promulgated by Andrew, granting certain rights to the Saxon inhabitants of Transylvania.
- The Golden Bull of 1242 issued by King Béla IV to inhabitants of Gradec (today's Zagreb) and Samobor in Croatia, during Mongol invasion of Europe. By this golden bull King Bela IV proclaimed a Free Royal Borough (free and royal city).
- The Golden Bull of 1348, issued by King Karel I of Bohemia, later Holy Roman Emperor as Charles IV, to establish Charles University in Prague, one of the oldest universities in the world.
- The Golden Bull of 1356 is probably the most famous golden bull, being a decree issued by the Holy Roman Emperor Charles IV. Its promulgation at the Diet of Nuremberg defined, for a period of more than four hundred years, the constitutional structure of the Holy Roman Empire.
- The Golden Bull of 1702, issued by Leopold I, Holy Roman Emperor to establish the Akademia Leopoldina in the Silesian capital of Breslau (present name: Wrocław), the future University of Breslau (Universitas Vratislatensis).
- Crowley, Roger (2012). City of Fortune: How Venice Ruled the Seas. New York: Random House. ISBN 978-1400068203.
- 750th Anniversary of the Golden Bull Granted by Bela IV
- M. Šašić (1998-11-17). "»Zlatna bula« - temelj razvoja Zagreba kroz stoljeća". Vjesnik (in Croatian) (Zagreb). Archived from the original on 2009-01-04.