Uses of Interface
org.bukkit.entity.Entity

Packages that use Entity 
Package Description
org.bukkit
More generalized classes in the API.
org.bukkit.entity
Interfaces for non-voxel objects that can exist in a world, including all players, monsters, projectiles, etc.
org.bukkit.entity.minecart
Interfaces for various Minecart types.
org.bukkit.event.block
Events relating to when a block is changed or interacts with the world.
org.bukkit.event.entity
Events relating to entities, excluding some directly referencing some more specific entity types.
org.bukkit.event.hanging
org.bukkit.event.painting
Events relating to paintings, but deprecated for more general hanging events.
org.bukkit.event.player
Events relating to players.
org.bukkit.event.vehicle
org.bukkit.inventory
Classes involved in manipulating player inventories and item interactions.
org.spigotmc.event.entity