Big Dumb Object is a term used in science fiction to describe any mysterious, typically large object of unknown (often extraterrestrial) origin which invokes a sense of awe just by existing. Although a BDO almost always has some greater purpose, this purpose will usually not be revealed to the characters or reader of a story initially. Instead, the plot is driven by the characters' attempts at finding and/or understanding the BDO. Naturally, the term "Big Dumb Object" intentionally deflates its true meaning.
Although coined by reviewer Roz Kaveney, Big Dumb Object was not in common use until it was included by Peter Nicholls in the Encyclopedia of Science Fiction as a joke.
Notable Big Dumb Objects include:
This is obviously not an exhaustive list. Big Dumb Objects make for interesting storylines, and are popular within the science fiction genre.