Several.
The Project Owner, who is ultimately responsible for the success of the project.
The Developer, who will do the lion’s share of the hands-on coding work during a development project, working closely with and under the guidance of the Project Owner.
The Tester, who will perform quality checks on the software to ensure it works as designed and to ferret out any bugs or inconsistencies before we release the software to the client.
The Project Coordinator, who helps projects get off to a good start, and then provides support to Project Owners to ensure their projects keep running smoothly.
The Product Owner, who owns the result of our work, builds consensus within the client team and makes decisions about the project in collaboration with the Project Owner.
A Collaborator, which is a generic term for any additional Developers, client team members, or vendor team members that join the project team to fulfill specific needs.
We discuss this whole topic in excruciating detail in our Process page.