This week, it's the turn of the cold. Not really a monster, but if you have read Shiver and Linger by Maggie Steifvater, then you will know just how much fear it can strike into Sam and the rest of the pack!
During summer the pack need not worry. The temperatures are high enough to keep them human. But soon, the cold will claim them forever and they will no longer make the change during warmer weather, living out the rest of their lives as a wolf.
Personally I think that the cold is one of the best used villains (okay, so it's not really a villain, but it is when it's getting in the way of true love!) in a romanced based series ever (okay, so I haven't read that many, but still!). Maggie Stiefvater uses the cold brilliantly and it just makes me want to read more!
Check out Shiver and Linger in time for the release of the third and final book, Forever next Summer!