Jonathan Hornblower (30 October 1717 – 7 December 1780) was an English pioneer of steam power, the son of Joseph Hornblower and brother of Josiah Hornblower, two fellow steam pioneers.
Jonathan was born in Staffordshire in 1717, the eldest of the four children of steam pioneer Joseph and Rebecca (née Haywood) Hornblower. Joseph Hornblower was an installer of Newcomen steam engines in the Cornish tinmines and taught his children the same trade. Jonathan eventually took over from his father around 1740 and moved to live and work in Cornwall, where he built and installed Newcomen engines at several mines.
He married Ann Carter of Broseley, Staffordshire, a lawyer's daughter, on July 16 1843 and fathered 13 children, all given biblical names beginning with J. Both Jabez Carter Hornblower and Jonathan Hornblower Jnr were to continue the family's steam engineering tradition. Jonathan Snr died in Cornwall on Dec 7th, 1788.