Marsilio Ficino (Italian: [marˈsiːljo fiˈtʃiːno]; Latin name: Marsilius Ficinus; 19 October 1433 – 1 October 1499) was an Italian scholar and Catholic priest who was one of the most influential humanist philosophers of the early Italian Renaissance. He was an astrologer, a reviver of Neoplatonism in touch with the major academics of his day, and the first translator of Plato's complete extant works into Latin. His Florentine Academy, an attempt to revive Plato's Academy, influenced the direction and tenor of the Italian Renaissance and the development of European philosophy.

Ficino was born at Figline Valdarno. His father, Diotifeci d'Agnolo, was a physician under the patronage of Cosimo de' Medici, who took the young man into his household and became the lifelong patron of Marsilio, who was made tutor to his grandson, Lorenzo de' Medici. Giovanni Pico della Mirandola, the Italian humanist philosopher and scholar, was another of his students.

During the sessions at Florence of the Council of Ferrara-Florence in 1438–1445, during the failed attempts to heal the schism of the Eastern (Orthodox) and Western (Catholic) churches, Cosimo de' Medici and his intellectual circle had made acquaintance with the Neoplatonic philosopher George Gemistos Plethon, whose discourses upon Plato and the Alexandrian mystics so fascinated the humanists of Florence that they named him the second Plato. In 1459 John Argyropoulos was lecturing on Greek language and literature at Florence, and Ficino became his pupil.

When Cosimo decided to refound Plato's Academy at Florence, he chose Ficino as its head. In 1462, Cosimo supplied Ficino with Greek manuscripts of Plato's work, whereupon Ficino started translating the entire corpus into Latin (draft translation of the dialogues finished 1468–69; published 1484). Ficino also produced a translation of a collection of Hellenistic Greek documents found by Leonardo da Pistoia later called Hermetica, and the writings of many of the Neoplatonists, including Porphyry, Iamblichus, and Plotinus.

Among his many students were Niccolo Valori and Francesco Cattani da Diacceto. The latter was considered by Ficino to be his successor as the head of the Florentine Platonic Academy. Diacceto's student, Giovanni di Bardo Corsi, produced a short biography of Ficino in 1506.

Though trained as a physician, Ficino became a priest in 1473. In 1474 Ficino completed his treatise on the immortality of the soul, Theologia Platonica de immortalitate animae (Platonic Theology) and De Christiana Religione (On the Christian Religion), a history of religions and defense of Christianity. In the rush of enthusiasm for every rediscovery from Antiquity, he exhibited some interest in the arts of astrology (despite denigrating it in relation to divine revelation), which landed him in trouble with the Catholic Church. In 1489 he was accused of heresy before Pope Innocent VIII and was acquitted.

Writing in 1492 Ficino proclaimed:

"This century, like a golden age, has restored to light the liberal arts, which were almost extinct: grammar, poetry, rhetoric, painting, sculpture, architecture, music ... this century appears to have perfected astrology."