Identifying a project's stakeholders and their concerns, agendas, and needs is the first task architects should perform when starting on new projects.
Who are stakeholders? They are the people who have some vested interest in the project. Naturally there are many stakeholders with any projectcustomers, targeted end users, operations (IT), developers, maintainers, management, testers, and so on. Stakeholders also include the architects themselves.
It is important to catalog project stakeholders, as the architect's role is to strike a balance between the (sometimes conflicting) concerns and agendas of stakeholders versus the project's functional/nonfunctional requirements. Stakeholder needs/concerns can impact the architecture. The most obvious example is a time constraint; for instance, "finish the project in two months or don't do it at all." Such constraints are bound to have an affect on the possible complexity of the architecture.
The place to start is to build a mental model of the stakeholders in the project. Keep in mind that the reality is that not all stakeholders necessarily want the project to succeed. You can map the stakeholders by their interest in the project, their power, and the importance of their concerns. As a rule, you should closely manage the stakeholders who have lots of interest in the project and who can influence its success. Keep stakeholders who have low interest but high influence satisfied; keep the stakeholders who are interested but have low influence informed, and monitor the rest (see "Another View at Enterprise Architecture Viewpoints," by J. Schekkerman; www.enterprise-architecture.info/Images/ExtendedEnterprise/E2A-Viewpoints_IFEAD.PDF).