John S. Gray (1833 – September 12, 1891) was a Republican politician from Idaho.

Gray was born in Watertown, New York, in 1833, and he moved West, to Yreka, California, in 1857.

He came to Idaho Territory in 1862, first to Orofino, then to Florence, before settling in Boise.

He lost elections for district attorney in 1864 and sheriff in 1868 before being appointed as territorial treasurer in 1871.

Gray then served as a delegate to the Idaho Constitutional Convention for Ada County in 1889.