Some or all of of a character's skin is made of metal. A common feature of many cyborgs and androids that aren't designed to look convincingly human, but it may also be the case with non-mechanical beings such as certain golems or elementals.
Don't use this tag unless the skin actually appears to be made of metal. Seams, overlapping plates, and a lustrous finish are valid reasons to use this tag. Skin that is simply grey or yellow is not; that's what the Grey Skin and Yellow Skin tags are for. Shiny coverings that aren't actually metal might be Scales or a Carapace.
This tag shouldn't be used for non-humanoid Robots or Mecha since they aren't typically meant to have "skin" anyway.