Messengers or head characters are beings either angel or other unknown beings. See Messengers (Canon) for more informaton.
Angel Zoe (D5) who appears to Natalie Faust and Nester Adrastos in Battlestar Hermes: Faststar (Story)
Messenger Guinevere (D8): who appears to Admiral Arthur Wallace in Battlestar Leonidas (Story)
Messenger Arthur (D8): whp appeard to Galit Malka (D8) in Battlestar Leonidas (Story).