Marco Barbo (1420 – 2 March 1491) of Venice was a cardinal of the Roman Catholic Church (1467) and patriarch of Aquileia (1470) who served in the capacity of cardinal-nephew to his cousin Pietro Barbo, Pope Paul II. In Rome he resided in the Palazzo di San Marco, as did the Venetian pope, who elected not to remove to the Vatican. From 1467 he was the cardinal patron of the Knights of Rhodes, for whom he built the loggia on the imperial forums.