I hate wraiths because you could just be walking around in a cave looking for important, and some wraith can just pop out-of-loving-nowhere and light you on fire, which is bullstuff. 90% of the time, you don't get a continuous burn. The other 10%, you just have to suffer until you actually have enough food to eat through the burn, or take a step into a water source.
Ogres? Bullstuff. When I first found the ogres, I thought they were pretty cool and I killed a few of them, until they used their alternative "Boulder Smash" attack, which basically destroys any block. Those mother forgeters will smash a million blocks just to get a jump on your ass. An example is, when I was making charcoal inside of my house, when I'm nearly done, a huge loving ogre just leaps out of nowhere, obliterates my house, and mauls me to death.
/rant