Giovanni Morelli (25 February 1816  – 28 February 1891) was an Italian art critic and political figure. As an art historian, he developed the "Morellian" technique of scholarship, identifying the characteristic "hands" of painters through scrutiny of diagnostic minor details that revealed artists' scarcely conscious shorthand and conventions for portraying, for example, ears. He was born in Verona and died in Milan.

Morelli studied medicine in Switzerland and Germany, where he taught anatomy at the University of Munich. During this time he also studied Goethe's morphology, Lavater's physiognomy, Friedrich Schelling's natural philosophy and befriended Bettina von Arnim. "Although Morelli qualified as a doctor, he never practiced as one.... His passion for anatomy and aversion to practicing medicine were consistent throughout his life."

Jaynie Anderson wrote:

The influence of Agassiz, as well as other scientists such as Cuvier and Darwin, combined with his developing interest in visual art and exposure to art historians of the calibre of Carl Friedrich von Rumohr, led Morelli to look at the art of the Italian Renaissance with an anatomist's eye. He found much greater satisfaction in the forms (Gestalten) of a Raphael, a Correggio, a Titian, a Michelangelo, or a Giulio Romano, than in the comparative demonstrations of osteology.

The Morellian method is based on clues offered by trifling details rather than identities of composition and subject matter or other broad treatments that are more likely to be seized upon by students, copyists and imitators. Instead, as Carlo Ginzburg analysed the Morellian method, the art historian operates in the manner of a detective, "each discovering, from clues unnoticed by others, the author in one case of a crime, in the other of a painting". These unconscious traces — in the shorthand for rendering the folds of an ear in secondary figures of a composition, for example — are unlikely to be imitated and, once deciphered, serve as fingerprints do at the scene of the crime. The identity of the artist is expressed most reliably in the details that are least attended to. The Morellian method has its nearest roots in Morelli's own discipline of medicine, with its identification of disease through numerous symptoms, each of which may be apparently trivial in itself. "Anatomical details were also important ... in determining authorship. For instance, with Titian the thumb is given a high rating, because Morelli identifies fifty works by that artist in which the base of a man's thumb is abnormally developed."

Morelli developed his method studying the works of Botticelli, and then applied it to attribute works to Botticelli's pupil, Filippino Lippi. His fully developed technique was published as Die Werke italienischer Meister in den Galerien von München, Dresden und Berlin (The work of the Italian masters in Munich, Dresden and Berlin galleries) in 1880; it appeared under the anagrammatic pseudonym "Ivan Lermolieff". Morelli's "great antagonist, the art historian Wilhelm von Bode, even spoke of the spread of an epidemic of "Lermolieffmania", after the mysterious Russian scholar "Ivan Lermolieff", the pseudonym under which Morelli published his writings, in the German translation by an equally non-existent Johannes Schwarze, a resident of the imaginary Gorlaw, which is to say Gorle, near Bergamo." Today, the Morellian method extends to cognate disciplines, including literary studies.

Morelli's connoisseurship was developed to a high degree by Bernard Berenson, who met Morelli in 1890. The first generation of Morellian scholars also included Gustavo Frizzoni, Jean Paul Richter, Adolfo Venturi and Constance Jocelyn Ffoulkes.

Morellian scholarship penetrated the English field from 1893, with the translation of his master work. The Morellian technique of connoisseurship was extended to the study of Attic vase-painters by J. D. Beazley and by Michael Roaf to the study of the Persepolis reliefs, with results that further confirmed its validity. Morellian recognition of "handling" in undocumented fifteenth- and sixteenth-century sculpture, in the hands of scholars like John Pope-Hennessy, has resulted in a broad corpus of securely attributed work. At the same time, modern examination of Classical Greek sculpture, in the wake of pioneering reassessments by Brunilde Sismondo Ridgway, has also turned away from attributions based on broad aspects of subject and style that are reflected in copies and later Roman classicizing pastiche.