Final answer:
The test manager is typically responsible for the creation and update of a test plan within a project, ensuring the testing phase is well-managed.
Step-by-step explanation:
In the context of a project, the person normally responsible for the creation and update of a test plan is the test manager. A test manager takes ownership and manages the project from beginning to end under the direction of the R&D manager and is responsible for full product testing. While the project manager oversees the entire project, including resource allocation and planning, and the product owner focuses on the vision from the stakeholders' perspective, the test manager specifically ensures that the testing phase of the project is carefully planned and executed following best practices and standards.