(Διογενειανός), a grammarian of Cyzicus, who is also called Diogenes (Suid. s. v. Διογένης), whence some have ventured upon the conjecture, that he is the same person as Diogenes Laertius, which seems to be supported by the fact, that Tzetzes (Chil. 3.61) calls the latter Diogenianus; but all is uncertain and mere conjecture. Diogenianus of Cyzicus is called by Suidas the author of works on the seven islands of his native country, on the alphabet, on poetry, and other subjects. It cannot be determined whether the Diogenianus mentioned by Plutarch (Sympos. 8.1), or the one from whom Eusebius (Praep. Evang. 4.3; comp. Theodoret. Therap. x. p. 138) quotes a fragment on the futility of oracles, is the same as the grammarian of Cyzicus or not. (Bernhardy, ad Suid. i. p. 1378.)