Final Fantasy XII - Rare Monsters

Rare Monsters (or Mobs) are those that aren't part of the Mark system in the game. There are two types of Rare Mobs, ones that will spawn infinitely, should you fulfill the conditions needed, and those that only spawn once and should you kill them, they do not spawn again. The second set are related to the Trophy Rare Monsters; talk to the Huntmaster in Hunters' Camp at Phon Coast (after clearing Draklor Laboratory). Doing so will grant you the option to hunt down Thalassinon, which is one of the Trophy Rare Monsters. Kill it and bring the Shelled Trophy back to the Huntmaster, then talk to either Atak, Blok or Stok to gain access to the other Trophy Rare Monsters. There are 49 normal Rare Monsters and 31 (including the one that's a prerequisite) Trophy Rare Monsters.