George Ord, Jr. (March 4, 1781 – January 24, 1866) was an American zoologist who specialized in North American ornithology and mammalogy. Based in part on specimens collected by Lewis and Clark in the North American interior, Ord's article "Zoology of North America" (1815), which was published in the second American edition of William Guthrie's Geographical, Historical, and Commercial Grammar (Johnson and Warner), has been recognized as the "first systematic zoology of America by an American".

Ord (1815) published the first scientific descriptions of Pronghorn antelope (Antilocapra americana), Grizzly bear (Ursus arctos horribilis), Meadow vole (Microtus pennsylvanicus), Bushy-tailed woodrat (Neotoma cinerea), Eastern gray squirrel (Sciurus carolinensis pennsylvanicus), Columbian ground squirrel (Urocitellus columbianus), black-tailed prairie dog (Cynomys ludovicianus), Bonaparte's gull (Chroicocephalus philadelphia), ring-billed gull (Larus delawarensis), Tundra swan (Cygnus columbianus), and Columbian sharp-tailed grouse (Tympanuchus phasianellus columbianus).

Ord is widely known for challenging the works of John James Audubon.

Ord was born and died at the same residence, 784 Front St., in Philadelphia. His mother was Swedish, and his father, Captain George Ord, Sr. (1741–1806), a celebrated naval captain during the American Revolution, was the proprietor of a rope-making business and served as Warden of the Port of Philadelphia. Ord joined the family business and continued it after his father's death.

Ord met Alexander Wilson in the summer of 1811, and accompanied him on two collecting expeditions (each four weeks duration) to Cape May, New Jersey, during the spring migration seasons of May 1812 and May 1813. During the 1812 trip, Ord collected a bird that neither he nor Wilson could identify. Wilson illustrated Ord's specimen and named it "Cape May Warbler / Sylvia maritima" in volume 6 of American Ornithology (1812), writing:

"This new and beautiful little species was discovered in a maple swamp, in Cape May county, not far from the coast, by Mr. George Ord of this city, who accompanied me on a shooting excursion to that quarter in the month of May last. Through the zeal and activity of this gentleman I succeeded in procuring many rare and elegant birds among the sea islands and extensive salt marshes that border that part of the Atlantic ; and much interesting information relative to their nests, eggs, and particular habits. I have also at various times been favored with specimens of other birds from the same friend, for all which I return my grateful acknowledgments."

The letter-press for volume 8 of American Ornithology (1814) was complete by August 1813, but Wilson's "great anxiety to conclude the work, condemned him to an excess of toil, which, inflexible as was his mind, his bodily frame was unable to bear." Wilson died of complications from dysentery on August 23, 1813; one week earlier, he named Ord an executor of his "last Will and testament". After Wilson's death, Ord completed the publishing and distribution, and compiled Wilson's unpublished writings for a final (9th) volume which contained an extended "Biographical sketch of Alexander Wilson".

Ord published a second edition of American Ornithology in 1824–25. The first 6 volumes were faithful reprints of the originals, confusingly so because they bear the dates of the first editions on their title pages (1808–12). In contrast, volumes 7–9 were revised and expanded by Ord and included a much larger version of his "Life of Wilson" (198 pp., versus 36 pages in the original 1814 version).