Pax Nicephori, Latin for the "Peace of Nicephorus", is a term used to refer to both a peace treaty of 803, tentatively concluded between emperors Charlemagne, of the Frankish empire, and Nikephoros I, of the Byzantine empire, and the outcome of negotiations that took place between the same parties, but were concluded by successor emperors, between 811 and 814. The whole set of negotiations of the years 802–815 has also been referred to by this name. By its terms, after several years of diplomatic exchanges, the Byzantine emperor's representatives recognized the authority in the West of Charlemagne, and East and West negotiated their boundaries in the Adriatic Sea.

The common belief that the negotiations between Byzantium and the Franks that were held in the early ninth century made Venice an 'independent polity' is only based on the late, allusive and biased witness of Venetian chroniclers such as John the Deacon and Andrea Dandolo and remains therefore highly questionable.