The son of an army major, Croker had little school education but did read widely while working in merchant trade. During rambles in southern Ireland from 1812 to 1816, Croker collected legends, folk songs, and keens (dirges for the dead), some of which he sent to the poet Thomas Moore, who acknowledged a debt to him in his Irish Melodies. This collection formed the basis of Researches in the South of Ireland (1824), a pioneering work of vast ethnography, and of his major publication, Fairy Legends and Traditions of the South of Ireland (1825–28), which was translated into German by the brothers Grimm and admired by Sir Walter Scott, who described Croker as “little as a dwarf, keen-eyed as a hawk, and of easy prepossessing manners.” After 1818 Croker lived in England, working as clerk in the Admiralty until 1850. His later works included Popular Songs of Ireland (1839).