What is the earliest that the shunned guardian motif appears?

Question

I would like to know what is the earliest work using what I call the shunned guardian motif.

What I mean by shunned guardian is a character (or organization) which guards the society from some external threat (usually monsters), but is himself shunned by that society.

Two modern examples I know of are claymores from the manga series Claymore and witchers (come to think of, both slay the monsters for money, ruinous amounts of it in Claymore).

Editing in a clarification from comments: the society is aware of the danger. It may have low probability or not be imminent, but they are aware of it.

Answer 1

One obvious example are the Rangers, the descendants of the northern kingdom of Numenoreans, who by the third age guard and watch over places like the Shire and Bree and are clearly shunned and misunderstood by Hobbits and Men alike.

A possible ancient example are the Fianna of Ireland (best known from the Fenian Cycle). These were landless aristocrats who spent the winter among society, but spent the summer "shunned" and foraging and fending for themselves.

Another possibility that comes to mind is Enkidu. Once created, he shuns civilisation and lives among the wild animals. He himself is shunned by civilised society though he eventually becomes the friend & guardian of Gilgamesh with whom a very great friendship evolves.