Hollis
This is my son's name (his middle name is John, a family name). It's an old English name that means "by the holly tree." It seems to be used about equally for boys and girls, but it's so rare that most people have never heard of it anyway, so the unisex factor is not annoying like in a Mason or Taylor name. Obviously I like it much better as a boy's name. I like unusual names with a real history.