Definition
The person accountable for the result of one cross-functional process, owning its metrics, its improvements and the closure of its abnormalities; every metric on a daily management board must point to a process owner.
In detail
A metric with no owner has nobody to turn the light off: every daily management case in the courseware names the process owner and their level before describing the boards and meetings, and that order is the answer. The owner is accountable for the result rather than for one department's segment, so the role needs to be able to convene people across functions rather than just manage its own slice. It differs from a functional manager at the boundary: the manager owns the resources of one function, the process owner owns one end-to-end chain; one person can hold both roles, but the two sets of metrics are not the same. It is also distinct from the "DBS Process Owner" — that role manages an item in the DBS toolbox (a tool or course), not the outcome of a business process. The official VSM instructor guide requires the process owner to be present when reviewing the current-state map, not the future-state map.
Example in practice
Order delivery spans sales, planning, production and logistics, and on-time delivery sits at 85 percentage points. After the supply chain vice president is named process owner and walks the overdue orders at the board daily, delivery reaches 95 percentage points within three months.