Harvey Yena is an American member of Group 93. He is mentioned by Edward Richtofen in a radio on Call of the Dead. He created the Hyena Infra-Dead as it is a reference to his name being H. Yena. He most likely wrote the following line on the chalk boards in Der Riese: "HYENA, Edward[1]I know it was you, why won't it work any more."
He also seems to be mentioned in the Kassimir Mechanism easter egg, for there are different ways to collect the "LUNA Letters", and HYENA is one of them.