Stephen Hales (17 September 1677 – 4 January 1761) was an English clergyman who made major contributions to a range of scientific fields including botany, pneumatic chemistry and physiology. He invented several devices, including a ventilator, a pneumatic trough and a surgical forceps for the removal of bladder stones. He was also a philanthropist and wrote a popular tract on alcoholic intemperance.
Stephen Hales was born in 1677 in Bekesbourne, Kent, England. He was the sixth son of Thomas Hales, heir to Baronetcy of Beakesbourne and Brymore, and his wife, Mary (née Marsham), and was one of twelve or possibly thirteen children. Thomas Hales predeceased his father, Sir Robert Hales, and his first son Sir Thomas Hales, 2nd Baronet (Stephen Hales' brother) therefore succeeded to the baronetcy in December 1693.