Baron Thomas Dimsdale FRS (29 May 1712 – 30 December 1800) was an English medical doctor, banker and politician who sat in the House of Commons from 1780 to 1790.

Dimsdale developed a particular interest in the prevention of smallpox by inoculation (variolation), a deliberate infection of the patient via the skin with a mild form of the disease to give protection against more virulent strains.

[5] The results were a success and Catherine rewarded Dimsdale with £10,000, a pension of £500 per annum, £2000 expenses and a Barony of the Russian Empire.

In case the results had produced adverse effects, the Empress had arranged for a relay of fast horses to be available to speed the Dimsdales out of the country.

[7] During the long preparatory period before the variolations he wrote Tracts on inoculation written and published at St Petersburg in the year 1768.