John Poyntz Spencer, 5th Earl Spencer (1835 - 1910) (known as the Red Earl because of his distinctive long red beard) was a British Liberal Party politician under and close friend of British prime minister William Ewart Gladstone.

He succeeded to the Earldom of Spencer in 1857. He served in a number of governmental posts; he served as Lord President of the Council and as First Lord of the Admiralty. Most famously, he served twice as Lord Lieutenant of Ireland, when in 1882 Lord Frederick Cavendish and T.H. Burke , the Chief Secretary for Ireland and the Under-Secretary for Ireland, were assassinated in what came to be known as the Phoenix Park Murders.

Outside politics, he was the man who introduced barbed wire to Britain.

|- style="text-align: center;" | width="30%" |Preceded by:
The Duke of Richmond and Gordon | width="40%" style="text-align: center;" |Lord President of the Council
1880–1883 | width="30%" |Succeeded by:
Chichester Fortescue

|- style="text-align: center;" | width="30%" |Preceded by:
The Earl Cowper | width="40%" style="text-align: center;" |Lord Lieutenant of Ireland
1882–1885 | width="30%" |Succeeded by:
The Earl of Carnarvon

|- style="text-align: center;" | width="30%" |Preceded by:
The Viscount Cranbrook | width="40%" style="text-align: center;" |Lord President of the Council
1886 | width="30%" |Succeeded by:
The Viscount Cranbrook

|- style="text-align: center;" | width="30%" |Preceded by:
The Lord George Hamilton | width="40%" style="text-align: center;" |First Lord of the Admiralty
1892–1895 | width="30%" |Succeeded by:
George Joachim Goschen