In this paper, we give characterizations of the classical generalized quadrangles H(3, q2) and H(4, q2), embedded in PG(3, q2) and PG(4, q2), respectively. The intersection numbers with lines and planes characterize H(3, q2), and H(4, q2) is characterized by its intersection numbers with planes and solids. This result is then extended to characterize all Hermitian varieties in dimension at least 4 by their intersection numbers with planes and solids.