Who Should Be Responsible For Implementing A Strategic Plan?
In one sense, everyone is ultimately responsible for USING a strategic plan, but in terms of implementation, the KEY player is the leader of the organization, often the CEO, COO, or other similar senior position. Strategic plans, or "grand plans" have to do, at least initially with the overall direction of the company or organization, so in theory, and often in practice it is the CEO that will be held accountable for results that should be generated through the implementation of a strategic plan.
That's not to say that others in the organization are NOT responsible. All managers will have some responsibilities for plan implementation, and communicating the essence of the plans to employees, but if a strategic plan fails, or the implementation is faulty, it's the CEO (or other leaders) that are responsible.
Regarding implementing a strategic plan, the buck stops at the top.