Thomas Sheasby, Senior (c.1740–1799) was a British civil engineer and contractor. His early work involved bridge construction, after which he went on to build canals, including several in South Wales.
Sheasby joined with Thomas Dadford and together they decided to tender for work on the Cromford Canal in 1789. However, they left the job when they received an offer for work on the Glamorganshire Canal in 1790.