Recall that a category C is *small* if the class of its morphisms is a set; otherwise, it is *large*. One of many examples of a large category is **Set**, for Russell's paradox reasons. A category C is *locally small* if the class of morphisms between any two of its objects is a set. Of course, a small category is necessarily locally small. The converse is not true, as **Set** is a counterexample.

Now, I can construct categories that are not locally small. However, what's the most common or most reasonable such category?