Daniel M. Harkness (September 26, 1822 – August 5, 1896) was an American merchant and businessman in Ohio. He played a role in the formation of Standard Oil in Ohio.
His older half-brother Stephen V. Harkness and younger half-brother Henry M. Flagler became two of the original five founding partners of Standard Oil, along with John D. Rockefeller. Daniel Harkness had persuaded Henry Flagler to move to Ohio when young and join him in his uncle's business. There Flagler met Stephen V. Harkness and John D. Rockefeller. Daniel Harkness became a major stockholder in Standard Oil and one of the wealthiest individuals of his day.
Family
Harkness was the son of Dr. David M. Harkness and his second wife, Elizabeth Morrison (Caldwell). His father had been widowed, and had a son Stephen V. Harkness from his first marriage. David died when Daniel was young. Later the widowed Elizabeth Harkness took her two sons and returned to upstate New York. There she married Isaac Flagler, a Presbyterian minister in Hopewell, New York. They had a son, Henry Flagler, Daniel's half-brother.
Early days & Standard Oil
In 1837, Daniel Harkness moved to Bellevue, Ohio from Hopewell, New York to live with his paternal uncle Lamon G. (LG) Harkness.