Peter I (born before 1020), also known as Petronius (French: Pierron and Italian: Petrone or Pietrone), was the first Norman count of Trani.
Though it had not yet been conquered from the Byzantine Empire, Peter received Trani in the Normans' division of Apulia made at Melfi in 1042.
After the division of 1042 Peter fortified the region around Trani, building new cities at Andria and Corato and re-fortifying Bisceglie and Barletta, as recorded by the chronicler William of Apulia (book II, lines 30–32): In 1046 he made his first assault on Trani, succeeding in capturing the suburbs and environs but not the city itself, which was defended by Argyrus, a former Norman ally.
Peter is recorded by Amatus of Montecassino as entering Melfi again in 1057 to dispute the succession with Drogo's younger brother Robert Guiscard.
In 1064, Peter's second son Geoffrey refers to his father as magni comitis Petroni in an act donating one ship to the monastery of the Santissima Trinità in Venosa for fishing on the Mar Piccolo, the bay of Taranto.