In Neil Gaiman’s novel The Graveyard Book, a man named Jack succeeds in killing all the members of a particular family except the young infant he particularly wants to murder. This infant, eventually known as Bod, happens to be absent from the scene of the crime when the killings occur. He is adopted and raised by the residents of the local graveyard, and only many years later, in Chapter 7, does he discover why the man named Jack – and indeed a group of men, all named Jack – want him dead.
In Chapter 7, one of the “jacks of all trades” reveals to Bod that
Long time ago, one of our people – this was back in Egypt, pyramid days – he foresaw that one day there would be a child born who would walk the borderland between the living and the dead. That if this child grew to adulthood it would mean the end of our order and all we stand for. . . . And we sent what we thought was the best and the sharpest and the most dangerous of all the Jacks to deal with you. To do it properly, so we could take all the bad Juju and make it work for us instead, and keep everything tickety-boo for another five thousand years. Only he didn’t.
The Jacks, therefore, tried to kill Bod to prevent the loss of their vast supernatural powers and to protect their strange and ancient “order.”