Grenville Lindall Winthrop (1864–1943) was an American lawyer and art collector from New York City.

[1] Winthrop co-founded a law firm in New York City with James B. Ludlow and Frederick Philips.

"[5] He was influenced from an early age by Charles Eliot Norton and his nephew, Francis Bullard, two prominent art collectors from Boston.

[2] He was assisted in assembling his collection by Martin Birnbaum, an art dealer from New York City.

[8] He owned the largest individual collection of paintings by Jean-Auguste-Dominique Ingres and William Blake.

[1] Additionally, he owned paintings by Edward Burne-Jones, Honoré Daumier, Jacques-Louis David, Vincent van Gogh, Winslow Homer, Pierre-Auguste Renoir, Auguste Rodin, John Singer Sargent, Henri de Toulouse-Lautrec, James Abbott McNeill Whistler, Gustave Moreau, Théodore Géricault, Eugène Delacroix, Théodore Chassériau, John Singleton Copley, Gilbert Stuart, and Aubrey Beardsley.

[1][7] Winthrop served on the Visiting Committee of the Fogg Art Museum at Harvard University for twelve years.

[1] They summered at Groton Place, a 150-acre estate spreading across the Baldhead Mountain in Lenox, Massachusetts, whose main house was designed by Carrère and Hastings and whose grounds included 500 peacocks and pheasants.

[1][7] Winthrop was described by art critic Richard Dorment as "a figure straight out of the pages of Henry James.