Not to mention that in the original example IValidator is invariant...it can be far more flexible by making it covariant (IValidator<out T>) so that GetAllValidators can also be used on more derived types.

And then you can do for example:

    var validators = GetAllValidators<EntityBase>();

Where validators might be IEnumerable<IValidator<EntityBase>>. Compile-time type safety is preserved and each individual validator's generic type can be any type that is derived from EntityBase.

:)