Robert Stevenson Horne, 1st Viscount Horne of Slamannan (1871-1940) was a Conservative British politician who served as Minister of Labour, President of the Board of Trade and Chancellor of the Exchequer under Lloyd George after the First World War.

When the Lloyd George Coalition Government fell in 1922, Horne refused to join the new government of Andrew Bonar Law. Two years later Stanley Baldwin offered to make Horne Minister of Labour once more, but Horne declined, preferring to concentrate on work in the City. Although he remained a Member of Parliament until 1937, he never again held ministerial office.

Horne was famously referred to by Baldwin as a "Scots cad", a remark that has stuck.