There are various types of Web Spinners produced from different species of spider. Some have been produced as B.O.W.'s, but others are Irregular mutants created by accidental viral exposure. These irregulars are simply labelled as "giant spiders". Virtually all of the different Spinner types possess the same abilities and behaviour, attacking humans and other animals on sight by mauling them with their feelers or by spewing acidic venom from their maws that can leave victims poisoned.The Umbrella Corporation developed the first Web Spinners at the Arklay Laboratory by injecting the T-virus into tarantulas. The results were unstable and the specimens proved to be uncontrollable, and so Umbrella abandoned the research. However, the T-virus outbreak occurred before all of the subjects were disposed of and many escaped and were allowed to roam freely throughout the mansion and the adjoining residence.
During the Raccoon City and Sheena Island incidents, numerous spiders became accidentally infected as the T-virus was scattered.