Pearl. The public, and even Hester at times, in the book sees her as a product of sin. She's probably a girl misunderstood by the whole community (who take every little "bad" thing she does and connects it to her being an illegitimate child) and brought up by a mother too distracted by her guilt to discipline her.
Roger Chillingworth. He is portrayed as wickedly and disturbingly obsessed, though Hester does note that she shouldn't have wronged him in the first place.
Actually he does little or nothing objectively bad (somewhat depending on interpretation). He has done a lot of good things though: at great personal risk he has learned medicine from the indians and uses it for the benefit of the community. He forgives Hester, even saying that her infidelity was mostly his fault, and medicates Pearl. He also lets her go, despite the fact that apparently he still loves her. He helps the man he suspects is the man who cuckolded him, even Dimmesdale admits that Chillingworth saved his life. Chillingworth correctly insists that Dimmesdale needs to fess up to whatever is on his conscience to truly regain his health. Yet everyone, including, the narrator, Dimmesdale, Hester and Chillingworth himself assumes he does all of these things for the worst reasons.
Anvilicious: Basically all the symbolism. Also, making Chillingworth ugly to show he was the bad guy.
Broken Base: The so-called introduction. Is it a fictional Framing Device or Hawthorne's real life behind the scenes essay (if this case it's also Based on a Great Big Lie). You'll find plenty of editions, including academic ones, that omit it as deeming it to be the latter.
Fair for Its Day: Hester Prynne can be considered a "proto-feminist" figure, being a single mother who earned her keep despite beingsomewhat attached to her stigma even after she's freed. It's notable too that unlike other literary Defiled Forever female protagonists, Hester got to live a full life, see to it that her child receive a good life, and die of old age. It helps that the text encourages us not to judge Hester for her actions and doesn't take a standpoint on how she should handle her situation.
Narm: In the film, the poor guy about to hang Dimmesdale gets shot by an Indian in the throat three times! And continues stumbling around in midst of the huge battle. It's almost a Overly Long Gag.
Seinfeld Is Unfunny: Suffice to say that most modern students who read the book in high school today (in a day and age where societal norms have changed) cannot see what the big deal is or why anyone would be so willing to accept a punishment the way Hester did. (Comparing English Lit and History is rarely suggested.)
Some Anvils Need to Be Dropped: A sin does not define a person as completely evil. How a person accepts and interprets his/her own sins are rift with complicated emotions and grey morality rather than the black and white.
Dimmesdale, would you just confess already?! You're wasting away.
Nicely averted with Hester. Although Hester is grieved and despondant at her place as an outcast, she gathers dignity to live and redeems herself gradually to her townsfolk — she is forced to take responsibility, and so she does so. Dimmesdale, her obvious foil, wastes himself away.
It is commonly taught in English classes the country over that the chapter "A Flood of Sunshine" is, in fact, one long literary metaphor for sex. Considering lines like, "All at once, as with a sudden smile of heaven, forth burst the sunshine, pouring a very flood into the obscure forest..." - well, is it any wonder?