The Alexander is a gin cocktail consisting of gin

Gin

Gin is a spirit which derives its predominant flavour from juniper berries . Although several different styles of gin have existed since its origins, it is broadly differentiated into two basic legal categories...

, Chocolate Liqueur (Crème de cacao), and Cream.

Recipes for Mixed Drinks, by Hugo Ensslin, 1915

Alexander Cocktail

• 1/3 El Bart gin
• 1/3 Crème de Cacao
• 1/3 Sweet Cream

Shake well in a mixing glass with cracked ice, strain and serve.

Variations

The most common variation of the Alexander is the Brandy Alexander, made with brandy instead of gin. Similarly, a Coffee Alexander substitutes coffee liqueur (such as Kahlúa

Kahlúa

Kahlúa is a Mexican coffee-flavored rum-based liqueur. It is dense and sweet, with the distinct taste of coffee, from which it is made. Kahlúa also contains sugar, corn syrup and vanilla bean.-History:...

) for gin, and a Blue Alexander substitutes blue curacao for crème de cacoa. Other variations exist.

In Jack's Manual (1910) there is another cocktail called The Alexander, this is a mixture of Rye Whisky

Rye whisky

Rye whiskey can refer to either of two types of whiskey: 1) American rye whiskey, which must be distilled from at least 51 percent rye; 2) Canadian whisky, which is often referred to rye whisky for historical reasons, although it may or may not actually include any rye in its production...

 and Bénédictine

Benedictine

Benedictine refers to the spirituality and consecrated life in accordance with the Rule of St Benedict, written by Benedict of Nursia in the sixth century for the cenobitic communities he founded in central Italy. The most notable of these is Monte Cassino, the first monastery founded by Benedict...

it is unclear whether or not this has any relation to the cream-based version.