Costain is a surname of English, Scottish and Manx origin.^[1] When originating in Scotland and northern Ireland the surname is an Anglicisation of the Gaelic Mac Austain, meaning "son of Austin". The English surname is a reduced form of Constant or Constantine.^[1]

People named Costain

• Molly Costain Haycraft (1911-2005), Canadian, author
• Albert Costain (1910—1987), British, politician
• Richard Costain (1839–1902), British founder of the Costain construction business
• Thomas B. Costain, (1885-1965), Canadian, journalist, author

Costain Nhemwa - a king of the modern age