Eau de Cologne (French for "water of Cologne"), or "cologne" for short, is a type of perfume. In its original formulation, it was an alcoholic and watery suspension or distillation of the oils of bergamot, lemon, orange and orange blossom, with the addition of lavender oil and rosemary oil.

Eau de Cologne is said to have been invented by Giovanni Paolo de Feminis towards the end of the 17th century. On October 8th, 1792, the Cologne merchant Wilhelm Mülhens received as a wedding present an old parchment with the recipe for "aqua mirabilis" (miracle water). He recognised the value of this gift and started to manufacture this Eau de Cologne (water from Cologne). However, Gianmaria Farina is also said to have acquired the recipe, and he started manufacturing an "Eau admirable" in 1714.

The use of the actual name "Eau de Cologne" is documented only from 1742. In 1810, Napoleon I decreed that it was only allowed to be sold as a perfume, not as a medicine. It was during the French occupation of Cologne that the brand name "4711" was coined. In order to tax the inhabitants more efficiently, all the houses in Cologne were numbered consecutively, and the house of the Mülhens family was house no. 4711. After seven generations of Mülhens managers, the firm was sold in 1994 to the Wella concern.

It is one of the few kinds of perfume to be widely worn by men.