Sir Samuel Alexander Sadler JP VD (1842 – 29 September 1911) was a British industrialist, public servant and the first Conservative Member of Parliament for Middlesbrough, United Kingdom, the town with which his name is associated.

Sadler was a chemist by profession and, having studied at the University of London, reputedly under Michael Faraday, he established the successful chemicals business of Sadler and Company Limited based at Middlesbrough – Teesside's first oil and chemicals company.

It was due to the efforts of pioneers such as Sadler that Teesside became established as a leading centre of the chemicals industry in the United Kingdom.

[5] He succeeded at the third attempt to be elected as the first Conservative Member of Parliament for the Middlesbrough constituency and unseated his predecessor Joseph Havelock Wilson in the firmly Liberal seat at the 1900 general election, but was defeated by Wilson at the 1906 general.

[6] In addition, he became a Freeman of the Borough, served as Justice of the Peace, Alderman and was honoured with a knighthood on 24 July 1905.