what charecter undergoes the most significant change during this play?

I think that John Proctor can be considered to be a dynamic character. Proctor certainly matures. He laments his behavior with Abigail, Instead of blaming his wife Elizabeth, for his affair, he places guilt squarely on his own shoulders. By the end of the play John has gone from self-righteous philandering to trying to keep any good that is left in his name.