Nobilissimus (Latin "most noble"), in Byzantine Greek nōbelissimos (νωβελίσσιμος)[1] was one of the highest imperial titles in the late Roman and Byzantine empires. The feminine form of the title was nobilissima.
It originated as an epithet to the title of Caesar, whose holder was the Emperor's heir-apparent and who would, after Geta in 198, be addressed nobilissimus Caesar.[2] According to the historian Zosimus, Constantine I first created the nobilissimus into a separate dignity,[1] so as to honour some of his relatives without implying a claim to the imperial throne. The title thus came to be awarded to members of the imperial family, coming in rank immediately after that of Caesar, and remained so throughout the early and middle Byzantine period, until the mid-11th century.[1] In to the Klētorologion of Philotheos, written in 899, the rank's insignia are described as a purple tunic, mantle and belt, indicating the exalted position of its holder. Their award by the emperor in a special ceremony signified the elevation of the recipient to the office.[3]
From that point on, the title was given to senior army commanders, the future emperor Alexios Komnenos being the first to be thus honoured.[1] The inflation of its holders during the Komnenian period led to its devaluation, and the new titles of prōtonōbelissimos and prōtonōbelissimohypertatos were created in the 12th century.[1]