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.
Cunningham was from an Ulster family. His father was Samuel Cunningham, and his elder brothers were Colonel James Glencairn Cunningham, Josias Cunningham stockbroker, Dunlop McCosh Cunningham owner of Murrays tobacco works, Belfast. He was sent to the Royal Belfast Academical Institution, and then to Fettes College in Edinburgh. He then won a place at Clare College, Cambridge - where he was heavy-weight boxing champion.
From 1931 Cunningham went into business in Northern Ireland. He married Dorothy Enid Riley JP on 2 July 1935. Later in the 1930s, Cunningham studied law and was called to the Bar by the Middle Temple in 1939. During the Second World War he served in the Scots Guards although he continued his legal studies, and called to the Bar in Northern Ireland in 1942. He fought the Belfast West byelection in 1943 and the same seat in the 1945 general election.