Giant creatures from the [[Suzumiya Haruhi no Yuuutsu]] series.

[spoiler]Whenever Haruhi is feeling depressed or moody, an area of closed space forms in a random area and these nasty creatures are summoned. Once summoned, these creatures will wreak havoc, changing the world to fit as Haruhi sees it. Only espers like Koizumi can seal away the celestials and prevent the destruction of the world as Kyon knows it.[/spoiler]
celestial (suzumiya haruhi)