The authors agree that this surname derives from a reduced form of the name Nicola. F. Miranda specifies that Cola is an aphaeretic form —that is, with the dropping of the initial syllable— of Nicola, which in turn comes from the Greek Nikólaos (Νίκόλαος), meaning "victor among the people".

E. Rossoni documents the transformation into a surname in Giuliana, in the Palermo area, during the 16th century, with the notary Giacomo Colletti, and in the Venice area in the second half of the 18th century, with the composer Giuseppe Colletti. Miranda notes that the surname is spread in about 160 comuni of a good part of the Italian regions: Sicily, Puglia, the Marche, Lazio, Emilia-Romagna, Campania, Piedmont, Lombardy and Veneto. In Sicily it appears with greater frequency in the provinces of Palermo, Trapani, Catania, Ragusa, Syracuse, Enna and Messina.

As for the variants, Miranda mentions Colletti and Colletto. Rossoni adds that Colletti has its main area in western Sicily, with specific presence in Lazio —in the provinces of Rieti and Rome— and in the Bologna area, while Colletto, very rare, appears in a specific way in the Palermo area and in the Venice area.