In Age of Conan attackable NPCs include a variety of animals, monsters and humanoids. When you target a NPC you will see their name, level and health. Additionally, you can get an idea of a NPCs kill difficulty by the color of the target ring.

Grey Target Ring: NPC is a much lower level than you, you will not receive XP or a challenge by killing it.

Green Target Ring: NPC is a much lower level than you, you will still receive XP for killing it, but not as much as you would receive by killing a higher level NPC.

Blue Target Ring: NPC is just slightly lower in level than you, the NPC should still pose a challenge and you will receive XP for the kill.

White Target Ring: NPC is the same level as you, but will pose a greater challenge, this fight could go either way. If you defeat this NPC you will gain more XP and have a chance to receive better loot than if you killed green or blue "cons" (Consider).

Yellow Target Ring: NPC is a slightly higher level than you. This will be a very tough fight and you might lose. However, if you win you will receive more XP than lower "cons" and have a chance to receive better loot.

Red Target Ring: Run! This NPC is well above your level, come back after you gain a few levels.