A stackable container assembly is disclosed, the assembly having a base container having a container body having a top surface and a bottom surface, an attachment base adapted for connecting the base container to a vehicle, and a fixture assembly attached to the top surface; and an accessory container having an accessory body having an accessory bottom surface, and an accessory base on the accessory bottom surface selectively connecting the accessory container to the fixture assembly of the base container such that the accessory container is stacked on top of the base container. A container and a vehicle provided with the stackable container assembly are also disclosed.