John Loudon

John Loudon is the name of:

• John Loudon (minister) (1866–1955), Dutch foreign minister (1913–1918)
• John Claudius Loudon (1783–1843), Scottish botanist
• John William Loudon (born 1967), Missouri state senator
• John Loudon McAdam (1756–1836), Scottish inventor of the Macadam Road Surface