How can MVC coexist with the Onion architecture?

I've seen people suggesting the implementation of MVC together with the Onion Archutecture. But how can the two coexist? Aren't they two distinct architectures? For example, where is the Controller in the Onion design?

I understand the combination of more than one design pattern, because they serve different purposes (behaviour, creation, etc), and can be independently implemented in different modules of the system, but I don't get how to implement two different architectures.