What character has gone through the biggest change and why?

I think that Hester’s transformation is most notable. She goes from resigned weakness to a strong sense of self and pride. Much of her transformation has to do with the redemptive powers that little Pearl exudes for Hester. She begins to see Pearl as a sign of all that is holy and good hence making her infidelity God's will rather than something to be ashamed of. Hester seems to exist separately from the hypocrisy and cynicism of the town.