Shrink ray

In science fiction, a shrink ray is any device which uses energy to reduce the physical size of matter.

In media:

In "In the Belly of the Boss", the third segment of The Simpsons Halloween special episode "Treehouse of Horror XV", the Simpson family is shrunk by Professor Frink.
A shrink ray invented by Professor Wayne Szalinski is featured in both the movie and TV Disney series "Honey, I Shrunk The Kids".
In Doctor Who, the Master uses a Tissue Compression Eliminator to shrink and kill people.
In the episode "Funny, They Shrunk Michaelangelo" in the 1987 Teenage Mutant Ninja Turtles cartoon, captain Talbot Breech uses a miniaturizing ray to shrink US naval ships and put them into bottles as revenge on those who turned him down for the US Naval Academy.
In the Aqua Teen Hunger Force episode "Unremarkable Voyage", Frylock builds a shrink ray (that can also enlarge items as well). Master Shake quickly gains control of the machine and proceeds to abuse it's power for his own welfare. The shrink ray turns out to be faulty, however, as items shrunk return to normal size after a period of time.

In games:

Engineers in the World of Warcraft are capable of crafting a Gnomish Shrink Ray.
The Eiffel Tower is reduced in size, then stolen, in the game Evil Genius
Duke Nukem 3D had a shrinker capable of shrinking an enemy.
In the Men In Black game "Crashdown" on the Playstation, Agent Jay uses a shrink ray to shrink himself so he may fight a group of alien insects.