Cultists are mysterious followers of Miraak, the first Dragonborn, who live in his temple on the island of Solstheim and carry out his wishes. Once you have been recognized as Dragonborn during the quest The Way of the Voice, a pair of cultists will be sent to Skyrim to hunt you and kill you for being a "false" Dragonborn. All cultists are powerful mages, relying on summoning and elemental magic spells in combat. The type of cultist you encounter depends on your level, and you will continue to meet low-level cultists even at high levels.
Cultists also carry a leveled dagger (iron, steel, orcish, dwarven, elven, glass, or an enchanted dagger of any quality from iron to Daedric). They also have a 10% chance to carry a leveled Conjuration or Destruction staff.
Master Cultists and Arch Cultists have the same miscellaneous items and daggers as other cultists, and have a 50% chance to carry a Staff of Chain Lightning, Staff of Fireballs, or a Staff of Ice Storms and do not have the leveled lists for atronach forge recipes.
These cultists have the ability to use Destruction magic as well, but prefer to summon flame atronachs and seekers to fight alongside them. They wear the same cultist's outfit as the cultists listed above, except Master Cultists and Arch Cultists, who wear the warlock outfit instead. Otherwise, their weapons, staves, and miscellaneous inventory items are the same as non-summoner cultists.