John Harold Spence (October 19, 1852 – March 27, 1929) was the son of Captain John Spence and Jane Harold of Southampton, Ontario. He was also known as "Jack Spence" and "John Jr.". He married Martha Rusk, of Southampton, in December 1878. He earned his master's (marine) certificate in 1874.

John H. Spence along with his father, Captain John Spence and his brother, Harry Spence, engaged in a coastal trading and lumber business businesses in the 1880s and 1890s. They also kept general stores in Pike Bay, Dyer’s Bay and Tobermory in Bruce County, Ontario. John H. Spence was also involved with the family's schooners, including Wanderer and Nemesis, which were used in the trade of Hemlock bark taken from Pike Bay to Southampton, Port Elgin or Goderich. The family also shipped Pike Bay cedar to the Detroit area and brought a pay load of supplies in return for their general stores.

John H. Spence was involved in the 1876 daring rescue of the steamer New York on the Michigan coast of Lake Huron during a vicious fall storm by his father, Captain John Spence, and his Schooner, Nemesis. John H. Spence received a silver medal for his role.