The surname Lanza has multiple independent ancestral stocks (ceppi), arising in different regions with no direct connection between them. Drawing on the studies referenced in the sources, it derives from a nickname linked to the word lanza, a regional form of lancia ("lance"), which probably alluded to the occupation of man-at-arms or weapon bearer. E. De Felice considers it a variant — both northern and southern — of the surname Lancia. E. Rossoni adds that a derivation from the medieval given name Lanza is also possible, documented as early as 1131 in the Codex Diplomaticus Brescianus, in a notarial deed drawn up in Brescia.

Rossoni records an early noble presence: in the 12th century a Francesco Lanza appears as a feudatory in Rosolini, in the area of Syracuse, and a Lanzi family is attested among the Ghibelline nobility of Trescore, in the area of Bergamo. In the 15th century the family figures in the patriciate of Capua. De Felice stresses that in Sicily the Lanza are one of the oldest feudal families, with branches including those of Trabia and Scordia. He also notes that the surname is frequent in Liguria, where it coexists with the form Lanzavecchia, and in the area of Naples.

The derived forms show differentiated distributions: Lanzetta is concentrated in the area of Naples and upper Salerno, with a lesser presence in the areas of Reggio Calabria and Palermo; Lanzetti appears in Piedmont, in the area of Rimini, and in that of Brescia; Lanzi extends across Lombardy, Emilia-Romagna, Tuscany, Umbria, and Lazio. It is also recorded as typical of the Sicilian communes of Partinico and Bisacquino, in the area of Palermo.