The Cowboy is a Prohibition era cocktail made with Scotch and cream.
It's been described as a "terrible drink" by Paul Dickson, added to later editions of Patrick Gavin Duffy's book The Standard Bartenders Guide.
[1] It also appears in The Savoy Cocktail Book by Harry Craddock.
[2] When dark rum is added, it's called a "Midnight Cowboy".
[3] It's shaken with ice and served in a cocktail glass.