Metamorphosis

Shape-shifting is the ability to alter one's physical shape into any number of desired effects. The limits to which are dependent upon the individual's level of power, aptitude and imagination. In some cases, effective use of shape-shifting also requires gaining or excising additional mass. A man who can shape-shift into the form of a fly must dispel the additional mass of his human body, which often dissipates into some undefined alternate dimension until such time that he resumes standard form, at which point, he can summon the discarded mass to instanteously restore him to normal.

There are some species of aliens who are shape-shifters, such as the Changelings featured in the Star Trek mythos, who can take the form of other alien races as well as animals. The character of Odo is the most well-known example of such a character. By his own admission however, he has difficulty assuming a human guise that is convincing to other humans, though he can satisfactorily take on the form of a Klingon.

In the Terminator film and television series, the T-1000 model of Cyberdyne Systems Terminators are comprised of a mimetic polyalloy, which enables them to take on any form they choose. When in an inert or injured state, the T-1000 assumes the form of a shining silver featuress humanoid.