Roles
There are three core roles[9] and a range of ancillary roles—core roles are often referred to as pigs and ancillary roles as chickens (after the story The Chicken and the Pig).
The core roles are those committed to the project in the Scrum process—they are the ones producing the product (objective of the project). They represent the scrum team.
Product Owner
The Product Owner represents the stakeholders and is the voice of the customer. He or she is accountable for ensuring that the team delivers value to the business. The Product Owner writes (or has the team write) customer-centric items (typically user stories), ranks and prioritizes them, and adds them to the product backlog. Scrum teams should have one Product Owner, and while they may also be a member of the development team, this role should not be combined with that of the Scrum Master. In an enterprise environment, though, the Product Owner is often combined with the role of Project Manager as they have the best visibility regarding the scope of work (products).
Team
The Team is responsible for delivering potentially shippable product increments at the end of each Sprint (the Sprint Goal). A Team is made up of 7 +/- 2 individuals with cross-functional skills who do the actual work (analyse, design, develop, test, technical communication, document, etc.). The Team in Scrum is self-organizing, even though there may be some level of interface with project management offices (PMOs).
Scrum Master
Scrum is facilitated by a Scrum Master, who is accountable for removing impediments to the ability of the team to deliver the sprint goal/deliverables. The Scrum Master is not the team leader, but acts as a buffer between the team and any distracting influences. The Scrum Master ensures that the Scrum process is used as intended. The Scrum Master is the enforcer of the rules of Scrum, often chairs key meetings, and challenges the team to improve. The role has also been referred to as a servant-leader to reinforce these dual perspectives. The Scrum Master differs from a Project Manager in that the latter may have people management responsibilities unrelated to the role of Scrum Master. The Scrum Master role excludes any such additional people responsibilities.
The ancillary roles outside of Scrum are those with no formal role and infrequent involvement in the Scrum process—but nonetheless, they should be taken into account, particularly in enterprise environments. In PRINCE2 project management terms, these encompass:
Project Manager
The individual responsible for the success of the project.
The Project Executive and Project Board
Those accountable for the project, particularly where issues and impediments need escalating outside of the Scrum team.
Project Assurance
The individuals with whom the Scrum team will consult in order to achieve their Sprint Goal, and with whom the Product Owner engages to understand what the ranked order of product backlog items should take in order to deliver enterprise value. The Project Assurance group consist of representatives of the Senior Supplier, Senior User and the Project Executive.
Managers
People who control the work environment.
Stakeholders
The individuals, not mentioned above, that often interface both with the Project Assurance group and with the Scrum Team. The stakeholders are sometimes customers, end-users, and vendors. They are people who enable the project and for whom the project produces the agreed-upon benefit[s] that justify its production. They may be involved in the Scrum process during the Sprint Review.