John Grimes Walker (March 20, 1835 – September 16, 1907) was an admiral in the United States Navy who served during the Civil War.

In retirement, he led commissions to investigate the construction of a Central American canal connecting the Atlantic and Pacific Oceans.

Walker distinguished himself under David Dixon Porter during the Mississippi River campaigns while serving in Winona, Baron DeKalb (which he commanded), and Saco.

He participated in the engagements with Forts Jackson and St. Philip, as well as the Chalmette batteries during the operations which resulted in the fall of New Orleans.

After commanding Sabine in 1869 and 1870—during which time he took the ship to Europe on a midshipman training cruise—Walker served as secretary to the Lighthouse Board from 1873 to 1878.

Promoted to captain in June 1877, he commanded the sidewheel steam frigate Powhatan on North Atlantic Station in 1881.

[2] Appointed permanent rear admiral in January 1894,[2] Walker briefly served as commander of the Pacific Squadron from April to August 1894.

Upon his return to shore duty in 1896, he headed the Lighthouse Board and concurrently chaired the committee investigating locations for deep-water harbors in southern California.