In the Classic World of Darkness, Pattern Spiders are the most basic kind of spider-shaped spirits working for the Weaver. They maintain the Pattern Web, and expand it by calcifying items, spirits, and people, then binding them into the Web. Net Spiders, Backdoor Spiders, Orb Weavers, Chaos Monitors, Nano Spiders, Channel Spiders, Guardian Spiders, Strand Spiders, Wolf Spiders, and Rail Spiders are all believed to begin their existences as Pattern Spiders, if only for a few nanoseconds. They may also be the origin of the Mula'Krante, Kilac'n, and Weaver-Spiders, but the former two are more closely associated with Cockroach's Brood and the Weaver-Spiders (or Weaver-Children) are quite mysterious. Pattern Spiders are not very self-aware and are implacable foes when they or the Pattern Web meet with resistance.
In Exalted, Pattern Spiders are the least members of the Bureau of Destiny and are charged with maintaining the Tapestry and the Loom of Fate. Sidereal Exalted often make deals with them in order to alter Fate to their advantage (or seeming advantage) in small ways.