John Penn (1805–1878) was an English marine engineer whose firm was pre-eminent in the middle of the 19th century due to his innovations in engine and propeller systems, which led his firm to be the major supplier to the Royal Navy as it made the transition from sail to steam power. He was also president of the Institution of Mechanical Engineers on two occasions.

The Institution of Mechanical Engineers (IMechE) is an independent professional association and learned society headquartered in London, United Kingdom, that represents mechanical engineers and the engineering profession. With over 120,000 members in 140 countries, working across industries such as railways, automotive, aerospace, manufacturing, energy, biomedical and construction, the Institution is licensed by the Engineering Council to assess candidates for inclusion on its Register of Chartered Engineers, Incorporated Engineers and Engineering Technicians.