  A bounded linear operator $ A$ on a Hilbert space $ \mathcal H $ is said to
be an $ EP $ (hypo-$ EP $) operator if ranges of $ A $ and $ A^* $ are equal
(range of $ A $ is contained in range of $ A^* $) and $ A $ has a closed range.
In this paper, we define $EP$ and hypo-$EP$ operators for densely defined
closed linear operators on Hilbert spaces and extend results from bounded
operator settings to (possibly unbounded) closed operator settings.
