Giant spiders are quite simply enormous versions of regular spiders. Existing in various types, there is no way to singularly describe their appearance; with various types ranging is size from that of a dog to a house. Giant versions of tarantulas exist, as do black widows, spitters, spinners and all manner of others. Their appearances, habits and environments all vary greatly. Goblins are known to employ them as mounts.
Giant spiders can attack in a variety of ways, typically whatever way their normal counterparts can. Some spin huge webs which prey easily stumble into, while others spit a deadly poison. Some are capable of walking on ceilings, while others are not. Despite the differences between the types of Giant spider, all are formidable opponents and certainly not foes for any arachnophobes to face.
Due to her nature, there are bound to be giant spiders serving the goddess Lolth.