Project manager in Agile projects

While most Agile methods have project managers or recognize their existence (e.g., DSDM^® and XP), Scrum is against it. Some people think that they can improve their Scrum projects by adding a project manager role, whereas it’s not compatible with the way Scrum is designed. On the other hand, some people think that having a project manager is against being Agile, which is completely wrong; it’s only unacceptable in Scrum and its derivatives, which is one way of being Agile but not the only one.