Ya'Vang was a Klingon captain and the commanding officer of the battle cruiser IKS SIm'yoH. In 2155, his ship was attacked and boarded by Romulans, but he sacrificed his life to eject himself and the boarding party into space. (ENT novel: Kobayashi Maru)

The acknowledgements for Kobayashi Maru indicate this character is the namesame of the IKS Ya'Vang.