Sir Samuel Knox Cunningham, 1st Baronet, QC (3 April 1909 – 29 July 1976), was a Northern Irish barrister, businessman and politician. As an Ulster Unionist politician at a time when the Unionists were part of the Conservative Party, he was also a significant figure in United Kingdom politics as Parliamentary Private Secretary to Harold Macmillan. His nephew was Sir Josias Cunningham.