Mastino I della Scala (died 26 October 1277[1]), born Leonardo or Leonardino, was an Italian aristocrat who founded the Scaliger house of the Lords of Verona.

From 1261 to 1269 he was podestà of the Casa dei Mercanti, a position which gave him control over all production and commerce in the city, and which he combined from 1262 on with that of capitano del popolo ("people's captain").

Mastino also obtained an agreement with the Republic of Venice which granted to the Veronese free access to trades on the Adige River and signed a treaty of peace with the Guelph city of Mantua.

Pope Clement IV, ally of the current King of Naples Charles I of Anjou, excommunicated Conradin and all his Ghibelline supporters, including Mastino and Verona itself.

Alberto himself, already appointed as his brother's successor as potestas mercartorum since 1269, was immediately voted to succeed Mastino as life-long captain and rector of the city, thus firmly establishing Verona as a lordship (signoria).