Don Ignazio Gaetano Boncompagni-Ludovisi (Rome, 18 January/June 1743 – Bagni di Lucca, 9 August 1790) was a priest and cardinal of the Roman Catholic Church.

Since 1754, Pope Benedict XIV gave his family all the benefices of the patronage that the Boncompagni Ludovisi exercised in the dioceses of Aquino and Sora, vacant since the resignation of Cardinal Pier Luigi Carafa.

In 1763, he was named by a bull of Pope Clement XIII as the archimandrite of the monastery of Sant'Adriano, diocese of Rossano; and abbot commendatario of Santa Maria di Giosefat in Cosenza.

In 1765, he became privy chamberlain of the pope and referendary of the Tribunals of the Apostolic Signatura of Justice and of Grace.

He remained in administrative positions in Bologna over the years, often proposing controversial reforms on land, water and tax management.