After WWII, a Greek soldier was returning home to merry his fiancée when he was captured by some fellow Greeks with opposing political opinions.
The poor guy was tortured for weeks before finally murdered. Now, this soldier is said to wander around, seducing young widows and virgins. After a time, the woman inevitably become pregnant.
After the baby is born, the soldier disappears, never to be seen again. All he leaves behind is a note saying:
I am not of the living. I had returned from the dead so that I may pass on my blood line. My only wish is that my sons can avenge my death.