Kaiju is the more common term for gigafauna, or organisms that are an order of magnitude larger than most animals. Individual kaiju are often unique aberrations, but some are alien in origin and may be considered normal for their species. Most kaiju in Hollywood are confined to Mondo Island unless leased out for film production.
Although cave paintings and prehistoric attempts at film have been discovered depicting what might be kaiju, the first recorded living kaiju was Mightosaurus in 1923. Though somewhat small by modern kaiju standards, its destructive rampage through the streets of Los Angeles provided hours of usable footage for film studios before being slain by aerial attack. Since then, kaiju rampages have been an occasional but fairly regular occurrence in Hollywood, sometimes started deliberately by studios but mainly a result of government underfunding.