Cuttlefish
Prevalent in nature (chameleons, cuttlefish and cephalopods), active camouflage is the adaptive and dynamic use of camouflage. In other words, camouflage which reacts to the environment around it to make the user undetectable. Its human applications have been firmly rooted in science fiction until now, but there have been some very recent advances in active camouflage technology.
The infamous Predator and his active camouflage.
Such advances include the use of Organic Light Emitting Diodes (OLEDs) and materials that bend light around them. While we won't see Predator style camouflage in the very near future, it's safe to say that rudimentary active camouflage will probably makes its debut very soon.
