Some roles with a lot of cinematic history behind them are: the disfigured victim; the scarred and vengeful villainess; and the heroine who is almost miraculously transformed into a beauty (often with disturbing side-effects). And, of course, the more beautiful the actress behind the makeup the more shocking the transformation.
This sub-section includes a number of characters whose heads have been shaved for brain surgery but most cases of hair loss (whether through illness or shaving) are included in the hairless characters section.