There are three roles in a Scrum project; no less, and no more. We are not allowed to define any other roles, because it is harmful to the unity of the team, and it is not compatible with the philosophy of Scrum.
A Scrum Team consists of the following three roles:
The term “Scrum Team” refers to all the project team members: everyone internal to the project. Scrum Team members usually have only one of the three standard roles of Scrum: Product Owner, Scrum Master, or Development Team member. It is possible for a single person to be assigned to more than one of the standard roles, but it is not recommended.
Other persons can also be involved in the project but they are not considered internal to the project and Scrum theory does not have much to say about them. They should have a certain set of behaviors though, to make it possible for a Scrum project to succeed.
The customer should understand and adopt the Scrum framework too, as the relation between the customer and the performing organization, and the way we deliver the project completely changes when we switch to the Scrum framework.
Note: in case of internal projects, the term “customer” will refer to another part of the company that orders the product and will probably use it in their operation afterward.
Other Roles and Titles
You might have the temptation to give Development Team members more specific titles, such as designer, tester, quality inspector, and team leader; but Scrum does not allow this. All members should have the same role, and the same title: Development Team member.
Scrum is completely depended on collaboration and team-work. Development Team members should be united and completely aligned with the goal of the project. If you give them different titles or roles, they will focus on their own specific role in the project instead, and they might not pay enough attention to the final product which is necessary for Agile projects. Each Development Team member is responsible for all the outputs created in the Development Team, even though each of them might be focused on a specific set of tasks.
There is no Project Manager role in Scrum; and none of the 3 roles of Scrum acts as a traditional project manager.
The project management responsibilities are distributed among the three roles of Scrum and there is no centralized project management in Scrum.
Note that having a project manager is not against Agility; it’s just not applicable to Scrum. Other Agile methods, such as DSDM, have project managers.
The Scrum Team has two essential characteristics:
- Self-organized: The Scrum Team manages its own efforts rather than being managed or directed by others. In traditional methods, management efforts are separated and centralized; a subset of the project team is responsible for project management and others are only responsible for specialist activities. However, management and specialist efforts are not separated in Scrum.
- Cross-functional: The Scrum Team has all the expertise and competencies needed to get the job done without any help from outside the team.
These two characteristics are designed to optimize flexibility, creativity, and productivity, needed for the Agile environment of Scrum.
It might be required to have more team members for larger projects. In that case, we can use multiple teams for a single product, and it is called scaled Scrum. Scaled Scrum should follow the whole Scrum framework nevertheless.
Scrum uses one team by default. You can "scale" it up and use multiple teams for a single project using Nexus, or another scaling framework.
- Scrum Guide, a definition of the Scrum framework by Ken Schwaber and Jeff Sutherland
- Nexus Guide, a framework for scaling Scrum by Ken Schwaber et al.
- The Scrum Master Training Manual, a free ebook on Scrum, and the Professional Scrum Master™ (PSM™ I) exam
- Scrum Awareness, a free email course on Scrum framework
- DSDM Awareness, a free email course on DSDM methodology