Theognostus of Alexandria was a third-century bishop and theologian from Alexandria. A student of Origen, he likely led the Alexandrian school following Pierius around 265. While he is not mentioned by Eusebius or Jerome, his intellectual contributions are preserved through the writings of Athanasius and Photios I. His theological perspectives, which blended Christian thought with Hellenistic philosophy, influenced later thinkers such as Gregory of Nyssa.