| Companion may refer to:
* A friend or acquaintance you associate yourself with
* Companion (caregiving), a nurse assistant or similar professional who assists a patient one-on-one
* Companion (ship), an architectural feature of ships
* Companion animal, a pet animal kept for companionship
* Companion parrot, a pet parrot that interacts with its owner
* Companion matrix, a matrix with a specific relation to its characteristic polynomial p
* Companion star, a star in a binary star system
* Companion weapon, an object held in the non-sword hand while fencing
* Muhammad's companions, the Sahaba
* Companion cavalry, Alexander the Great's elite cavalry
* Foot Companion, the primary type of soldier in Alexander the Great's army
* Lady's companion, a genteel woman who acted as a companion for woman of rank or wealth
* Sober companion, an addiction treatment coach
* Companion planting, planting of different crops in close physical proximity
* A handbook or guide book or compendium e.g. Star Trek: Deep Space Nine Companion or The Oxford Companion to Music
* A member of a Holy Royal Arch chapter
* A domestic partner
* A concubine
* An intelligent conversational agent as in the Companions Project
* An companion in the Islamic religion: Sahabah |