Guard

The vault guards are an exceedingly rare NetHack monster. They will appear occasionally when a player is looting a vault (Suddenly, one of the vault's guards appear!) and will accost the player.

In most circumstances, the guard will ask your name (with a small alignment penalty for lying if you are lawful) and then demand that you drop all of your gold ("Most likely all of your gold was stolen from this vault.") and follow them out of the vault (via a passage that appears with the guard). If you comply, the passage and guard will disappear once you have reached the end of the passage; if you do not, or attempt to escape by some other means (such as teleportation), the guard will turn hostile and attack.

There are several ways to avoid fighting a guard:
 * Tell them your name is Croesus (or Kroisos or Creosote); if Croesus has not been killed the guard will leave in peace. If Croesus has been killed, however, the guard immediately turns hostile, without the chance to pacify them by dropping one's gold.
 * Eat a mimic corpse, which temporarily transforms you into a pile of gold; if the guard appears while you are in this state, they will turn around and leave, puzzled. (If you are hallucinating, you turn into an orange instead; the guard will still leave - "Hey!  Who left that orange in here?")
 * Do not stick around long enough in the vault to let them appear.