Gennaro (Janvier) D'Alessandro or D'Alessandri, Alexandre, Allexandro, D'Allessandria (1717?

– after 28 July 1778)[1] was an Italian Baroque composer and harpsichordist.

[2][3] He was a pupil in Naples of Leonardo Leo, later he became maestro di coro at the Pio Ospedale della Pietà in Venice from 21 August 1739 to 13 May 1740, then harpsichord master of Madame de Martenet and Germain-Anne Loppin de Montmort in Dijon (from 1 October 1740 to 1749), Charles-Catherine Loppin de Gemeaux, Madame de Noinvilles and Madame de La Pouplinière in Paris (1743).

Back in Naples he was also singing master of Madeleine-Zoé-Anne-Marguerite Seimandy (1778) and participated in some accademie di musica at the Villa Angelica of William Hamilton together with Emanuele Barbella (1768).

He met prominent figures such as Frederick Christian, Elector of Saxony, Willem Carel Dierkens, Anton Raaff, Antonio Vivaldi, Carlo Goldoni, Alexandre Le Riche de La Poupelinière, Jean-Joseph de Mondonville, Charles de Brosses and Giacomo Francesco Milano Franco d'Aragona.