Xenophobia is the fear of strangers, but has come to mean the fear of any person or group that is foreign to our own comfortable assumptions. It can develop as a hatred towards races at a cultural level, or at a more micro level it could be the unreasonable hatred of people not within your social group (cheerleaders hating chess club members).
We all make assumptions about people, that's our overactive imaginations showing they work, but how that manifests into our behaviour will reveal whether we are xenophobic. Most of our stories will have at least one xenophobic character. In my fantasy novel The Costume Maker, my trio travel to another world where they come across three very different communities, each hating the other. I'm not sure if wars start from xenophobia (or if they are more politically devised for more sinister ulterior motives), but they are certainly propelled by it. Governments have been known to use people's mistrust and fear of the unfamiliar to allow them to differentiate themselves from the target culture, the way we disassociate ourselves from a different species. I guess this just makes it easier to hate.
So who's xenophobic in your novel? Matilda just posted a book review on Paper Dolls about a novel where a family find a bunny and take it in, the suspicious cat thinks this bunny is a vampire and therefore fears it, it turns out maybe a little understanding was needed instead. Check out Bunnicula.
X also marked the spot yesterday - it was my birthday and I had some wonderful surprises. It was also sweet to see many good cheers sent my way via Facebook. Thanks Facebook, I would forget many of my own family's birthdays if it wasn't for you.