George Nidever (also spelled Nidiver) (December 20, 1802 – March 24, 1883) was an American mountain man, explorer, fur trapper, memoirist and sailor. In the 1830s he became one of the first wave of American settlers to move to Mexican California, where he made his living in fur trapping. In 1853 he led the expedition that rescued Juana Maria, the last member of the Nicoleño people, from San Nicolas Island where she had been living alone for eighteen years. Toward the end of his life Nidever wrote a memoir, Life and Adventures of George Nidever, which was popular at the end of the 19th century.
Nidever was born in Tennessee, and was of German descent. At 28 he joined a hunting and trapping party in 1830 at Fort Smith, Arkansas that also included Isaac Graham and Job Francis Dye; after a year spent adventuring from Missouri to Texas the core of the party reached Taos in 1831. That fall they set out for the headwaters of the Arkansas River. Nidever took part in the battle of Pierre's Hole. From there the original Fort Smith group broke up, and in July 1832 Nidever joined Joseph Reddford Walker and accompanied him to California in 1833. Remaining there, he joined George C. Yount in a sea otter hunt which had some success. From Santa Barbara he renewed sea otter hunting, pursuing that profession, along with farming and Pacific piloting for the remainder of his life. He married California native Sinforosa Sánchez at Mission Santa Barbara in 1841.