Giovanni Battista Maini was an Italian sculptor of the Late-Baroque period, active mainly in Rome.
He was born in Cassano Magnago in Lombardy, and died in Rome. He may have had contacts with Foggini in Florence. By 1708, he had moved to Rome where he joined the large studio of Camillo Rusconi, where he worked for over twenty years. Among his first commission was the execution in bassorilievo of the Glory of San Francesco for a Jesuit church of Madrid; however, the bassorilievo in stucco, likely originally a design by Rusconi, was never sculpted in marble. Like Rusconi, Maini always modelled his projects in stucco first.
Maini collaborated in the decoration of the spandrels of the cupola of the Santi Luca e Martina. He worked in Sant'Agnese in Agone, where he executed the papal funerary monument to Innocent X, likely based on Rusconi’s designs. For St. Peter’s Basilica, Maini carved large marble statues of St Francis of Paola and St Philip Neri. This was part of a series of sculptures on the founders of orders and included Michelangelo Slodtz's St Bruno. He completed the Archangels Michael and Gabriel statues for the basilica of Mafra, commissioned by king of Portugal.