Arguably, the most important role involved in scrum is the Stakeholder, as the Stakeholders are the ones who have desires, wants, and needs, and are the reason the Team is developing the software in the first place. Often, there is a special stakeholder called the Business Owner, who actually controls the budget for the Team. The Business Owner is often the one who called or asked the team to form.
While the Stakeholders are the most important source of validation for the project, the most important person on the Scrum Team is the Product Owner (PO). The Product Owner works with the Stakeholders, represents their interests to the Team, and is the sole Team Member held accountable for the product the Team builds. The Product Owner must find a result that will satisfy the Stakeholders needs and desires. The Product Owner provides direction and goals for the Team, and prioritizes what will be done. The Product Owner connects the team with the purpose.