Tokyo ghoul's Kaneki's change in hair color
His hair turned white and nails turned black because of the physical and mental stress (the episodes in which Yamori tortured him)

It is mentioned @Wikia :


  After being tortured by Yamori for a period of ten days, his hair
  became white and his nails turned black due to heavy stress, anxiety,
  and continuous bodily regeneration. This condition is known as Marie
  Antoinette syndrome. It is caused by extreme stress or emotional
  trauma like he had undergone. He also began wearing a form fitting
  black outfit when he had the intention of fighting as a ghoul, both
  for intimidation and practicality.