As soon as the reader meets Chillingworth, he is not an attractive man. He emerges from the woods in a mixture of Native American and European dress with one shoulder slightly higher than the other. However, as the novel continues, Chillingworth's apperance continues to change as well.
Chillingworth has made it his goal to find the man who sinned with Hester. As his quest takes over his life, he grows more and more disturbing. In Chapter 14, the narrator describes this change in Chillingworth's apperance. This change shows that as the evil has taken over his life and soul, the evil is becoming evident on his outward appearance as well.
In a word, old Roger Chillingworth was a striking evidence of man's faculty of transforming himself into a devil, if he will only, for a reasonable space of time, undertake a devil's office. This unhappy person had effected such a transformation by devoting himself, for seven years, to the constant analysis of a heart full of torture, and deriving his enjoyment thence, and adding fuel to those fiery tortures which he analysed and gloated over.