Jupiter Grabovius is the chief god of the Umbrian community of Iguvium (modern Gubbio), known from the Iguvine Tablets, the most extensive surviving body of texts in the ancient Umbrian language. As the first member of the Grabovian triad he corresponds to the Roman Jupiter and embodies sovereign and celestial authority over the city. In the central lustration ceremony he receives three oxen before the Trebulan Gate, the first of the three gates around which the purification of the people was organised. His cult-title Grabovius, shared with Mars and Vofionus, is widely read as 'of the oak' or a related tree-name, marking the triad as gods of the city's sacred boundary and its protective enclosure.