Many different instances; most container shipping lines have vast stocks of their own containers, usually identifiable by the convenient advertising space on the sides. This variety is easily seen when containers are seen stacked aboard or in port, as in this picture:

ship containers
evergreen
shipping company

It’s worth noting that a container being owned by a carrier or forwarder doesn’t mean it’ll necessarily be carried by them – the containers can be rented or leased to customers (or sold outright) and transshipped all over the world.