Tom Collins

The Tom Collins is an American cocktail invention made of:

1 part gin
lemon juice
sugar
splash of soda

Shake gin with lemon, sugar and ice. Pour into a Collins glass and top with soda. Garnish with an orange slice, lemon slice, or cocktail cherry. The garnishes vary by region.

Nowadays, the club soda, lemon juice, and sugar are replaced with a mix.

Various versions replace the gin and rename the drink:

Brandy Collins (Brandy)
Jack Collins (Applejack)
John Collins (Bourbon)
Mike Collins (Irish whiskey)
Pedro Collins (Rum), also Rum Collins
Sandy (or Jock) Collins (Scotch)
Vodka Collins (Vodka)