My name is Kristen. For many years it was quite an unusual name to have and many European people said it's a boys name in all countries except Denmark. My mother had borrowed the name from a Danish friend she met years ago.
However, since Kristen attempted to kill JR on Dallas all those years ago it has become increasingly popular and in the US, UK, Australia etc mainly as a girls name.
There are many variations, some which can be both for girls and boys and some which are more for one gender. Like Kirsten, Kristian, Kirsten, Kristin, Kirstin etc. Obviously it means 'a christian'.