Unique

A "unique" is a one-of-a-kind monster, typically stronger than most monsters encountered at the stage of the game where the unique is likely to be encountered. A unique normally has a personal name (most monsters in most roguelikes do not) and may have more descriptive text or distinguishing features. In certain cases in some games, uniques fill special roles, like giving out quests or providing certain information. In other cases, a unique is just a chance for a slightly more distinctive fight.