These are disguises that achieve a radical change of the character’s appearance changing age, ethnic background or sex. In some cases the character explicitly uses prosthetic makeup but in others the change is supposedly the result of wearing a mask or of plastic surgery. The high level of skill required to make and apply the prosthetic or mask disguise is often explained by making the character or her helper an actress or makeup artist.
There are further examples of disguises using extensive prosthetics in the fakeovers section.
When the disguise is shown being removed there is often a bit of trickery with a cut to the actress removing a pull-off mask (even where we’ve seen the prosthetics being glued on to her face as in F/X: The Illusion!): in other movies a character supposedly wore a mask but the actress was clearly wearing prosthetic makeup (eg Penelope). Because of this there is a degree of overlap between this section and mask tricks.