Elite Monsters is a collective term for all kinds of monster types in Diablo III that are above average in power. It is most important to players when determining the effects of item affixes 'X% reduced damage taken from elites' and 'X% more damage dealt to elites'.
Overall, the elite monsters include:
- Treasure Goblins, even if they are of white color
- Illusionist affix illusions spawned by either of the above
Damage to / from elites modifiers are not a common roll, and will mostly occur on legendary and set items. Only weapons and off-hand items can roll damage against elites as normal affixes, and only chest armor can roll reduced damage from elites. One may also socket a Diamond into a weapon for increased damage against elites. These stats are very important in the endgame, when common monsters become a much lesser threat than the elites.