Lieutenant-Colonel John Stoughton Dennis (19 October 1820 – 7 July 1885) was a Canadian surveyor, militia officer, and civil servant.
In 1866, Dennis led an ill-fated militia attack against the Fenians at Fort Erie. Dennis is noted for his role in precipitating the Red River Rebellion by his 1869 surveys of the Red River Colony. He was the father of Colonel John Stoughton Dennis Jr., who also became a noted surveyor and militia officer .
In 1882 he was created a Companion of the Order of St Michael and St George.