The Reverend Hale is the most obviously dynamic character in The Crucible. He enters the play as a self-confident expert, eager to perform a task for which he believes himself to be exceptionally well prepared. In Act II, he seems increasingly assailed by doubt. He visits the Proctors to ascertain for himself the Christian character of their home and is evidently perturbed at the arrest of Rebecca Nurse and Elizabeth Proctor. When John Proctor calls him a coward and orders him out of the house, he has no reply except to say that there must be some reason, unknown to any of them, for what is happening.

In Act IV, Hale has changed completely. He regards the court as grossly unjust and bitterly regrets his own part in the proceedings, pleading with the obdurate Danforth to relent. He says that he counts himself guilty of John Proctor's murder and that he has been doing the Devil's work, counselling "Christians they should belie themselves."

Another dynamic character is Mary Warren, who changes from being a timid, put-upon servant girl in Act I to a self-important official of the court in Act II. In Act III she changes again as she attempts to tell the truth but is finally overwhelmed by Abigail's histrionics. In the progression from insignificance to self-aggrandizement to hysteria, she is representative of the other "children" who make false accusations and drive the witch-hunt forward (with the exception of Abigail, whose manipulative nature is already evident at the outset).

A dynamic character is a character that undergoes an important inner change throughout a story. Throughout the play, both John Proctor and Reverend Hale are considered dynamic characters because they experience dramatic internal changes throughout the play. 

At the start of the play, John Proctor is filled with guilt for cheating on his wife and refuses to provide the Salem court with the valuable information that Abigail and the other girls are lying. He also values his reputation, which is another reason he refuses to disclose his affair with Abigail to court officials.

As the play progresses, Proctor's wife gets arrested, and he decides to travel to Salem to expose Abigail as a liar. By the end of the play, Proctor not only sacrifices his positive reputation by openly disclosing his affair with Abigail but also signs his own confession. In one of the most dramatic scenes in the play, Proctor tears up his confession and atones for his past sins by refusing to sell out his friends. Proctor changes from a relatively selfish, private individual, to an outspoken dissident, who finds redemption by becoming a martyr.

Reverend Hale is also considered a dynamic character throughout the play. At the beginning of the play, Reverend Hale is an eager specialist, who hopes to discover witchcraft throughout the community of Salem. He is firm supporter of the court. He views every citizen as a possible witch and truly believes that dark spirits inhabit the community.

Over time, Reverend Hale becomes suspicious about some of the people being accused of witchcraft and begins to conduct his own independent investigations. By the end of act 3, Reverend Hale realizes that the court is corrupt and the goals of the court officials are simply to maintain their authority. By the end of the play, Reverend Hale does not believe that witchcraft is rampant throughout Salem and encourages the accused citizens to falsely confess in order to save their lives. Reverend Hale changes from being an adamant supporter of the court and leading figure in the witch hunt to a guilt-filled man, who dedicates his time to challenging the corrupt court.

One intensely dynamic character in The Crucible would have to be Reverend Parris.  At the start of the drama, he is scared as to what the implications of witchcraft will be upon his own stature.  In the middle of the drama, he has changed to embrace the popularity and sense of power that the trials have given to him.  The fear he once showed is gone and in its place is brazen displays of power in the courtroom and throughout the town.  By the last act, he has changed again, afraid of the backlash that the trials have caused.  Parris is a shell of what he once was, confessing fear for his life and displaying a willingness to do anything to save Proctor in order to make himself look good to a public that has effectively repudiated him.  Parris' ending fate as leaving Salem, walking alone on a road from town, is a fitting image that shows the dynamic nature of his characterization.

Certainly, another dynamic character from The Crucible would have to be John Proctor.  His dynamic characterization is what helps to make the drama so powerful.  Proctor's change from a man who does not want to get involved, to one who is hesitant about his involvement, to one who has no regard for anything else other than "his name" is powerful.  When Proctor is seen through the prism of one who dismisses Abigail as one who will always be troublesome with almost a wink to the man who stands up screaming about "his name" and what it means to him and his legacy, one sees the intense level of his change.  In both dynamic characters, the drama's compelling elements are present.