The Heretic

The Heretic is a traitor to The Church and/or its Canon. Most commonly, he was once a member of its congregation or even its clergy but got officially excommunicated for propagating beliefs that go against The Church's official dogma. Often, the Church sends out Knights Templar to Kill Them With Fire along with witches. Just being a heretic doesn't mark you evil by default: A heretic to a Saintly Church is often Chaotic Evil, but a heretic to a Corrupt Church or a Path of Inspiration may well be a Defector From Decadence.

To qualify as a heresy worthy of condemnation, the "heresy" should have an intrinsic connection to doctrines of the church in question. Someone who merely disagrees with the Church as an outsider is not a heretic - for instance, Hypatia of Alexandria. Wiccans are not considered "heretics" to the Catholic religion, but Padre Ned Reidy was put on trial for heresy.

The word "heretic" is from a Greek word meaning "to choose," so a heretic can be thought of as a person who chooses his own path. Christian theologian Irenaeus popularized the word heresy in the Christian world in his anti-Gnostic tracts. Multiple heretics often form a Cult.

Anime

 * Lenard and Elfetine's sect in Scrapped Princess. However, their "heresy".
 * Heresy is a common charge leveled against people in Berserk, particularly by those who serve the Holy See. The Count from the third major manga story uses the charge of heresy to get himself people to eat, being an Apostle. And Mozgus in particular is very much merciless in dealing with those who he considers heretics.
 * Arachne from Soul Eater is described as a "heretic Witch" because of the way she created the original magical Weapons features in the series. Taking a normal human soul, a weapon as well as the Soul of her fellow Witch (holding the power of transformation) she created them. Thus she's hunted not just by the good guys but her fellow Witches.

Literature

 * The Damned One is the history's greatest heretic in Arcia Chronicles. The twist in his case is that he is actually.
 * The Name of the Rose, by Umberto Eco, entirely revolves around the theme of the thin line between orthodoxy and heresy, and what happens when people cross it.
 * Nicholas Harpole in In The Garden of Iden.
 * In David Eddings' The Redemption of Althalus, one of Althalus' major enemies is a "defrocked" priest.
 * From the same author, there's Recurring Villain Martel in the Elenium, a former Church Knight who turned to the worship of the Dark God Azash and committed various atrocities since.
 * The Church in the Safehold series brands the entire nation of Charis as being heretics, mainly because they had the gall to survive the Church's attempts to obliterate them out of sheer paranoia. So far, despite having called down a holy war upon the Charisians, they have yet to learn that many of the leaders of Charis really are heretics, although the heresy they believe in (That the Archangels were not really divine messengers) is actually true.
 * In the Disgaea novels we meet angel Ozonne who propagates beliefs that go against Celestia's official dogma and is considered to be a heretic, but she is not excommunicated for it because the big boss Seraph Lamington want to let heretics run free.
 * The Preacher in Children of Dune certainly counts as this. He wanders the cities and settlements on the planet Arrakis, speaking out against the religion that has grown around the late Paul Atreides and his sister Alia. Of course it turns out that

Live Action TV

 * The reformation had just started at the start of The Tudors, but gained momentum as the series went on. Because of that the list grew ever longer. Here goes: Anne Boleyn, Thomas Cromwell, Archbishop Cranmer, Thomas Boleyn, Catherine Parr, Anne Parr, Edward Seymour, Anne Stanhope, Thomas Seymour, The Duchess of Suffolk, Kate Ashley and Anne Askew. Some of them suffered for it, all the others at least lived in fear of discovery.
 * Elizabeth and Edward are also raised this way.
 * During the course of the series quite a few minor characters got burned and tortured for this reason as well.

Tabletop Games

 * Warhammer 40000's theocratic Imperium of Man has a saying: "light your way in the darkness with the pyres of burning heretics." The civil war that almost destroyed it after its founding is labeled the Horus Heresy, there's an entire Ordo of the Inquisition devoted to rooting out heresy, and being executed for heresy is just one of the many ways to die in the setting. Some would say this can be exaggerated into an overused meme, but that would be "HERESY!"
 * *BLAM*
 * Seen every now and then in Eberron.
 * Exalted: Anyone working with the Anathema (that is, anyone working with your player character).
 * There is a growing number of these in Autochthon. And sometimes they are right.

Video Games

 * Roa from Tsukihime got excommunicated for becoming a vampire on his quest for immortality.
 * The eponymous character from Heretic, of course. The Heretics in question were the Sidhe elves, the only race of beings not subject to the sorcerous mind control of the Serpent Riders, and thus targeted for extermination by their minions.
 * The Heretic from Halo 2, an Elite who learned the truth about the "Great Journey" from 343 Guilty Spark and tried to warn the others. The Arbiter is branded a heretic at the beginning for his failure in the previous game, but that's really just an excuse to have him executed for his failure. Though later he does join the "heathen" humans and renounces all believes of the Covenant.
 * Ramza gets branded as one when he runs afoul of their Ancient Conspiracy and kills a (demon-possessed) bishop in self defense. On the other hand, Olan Durai is also burned at stake for trying to reveal the truth behind The Lion War and Ramza's unsung heroism.
 * Billy from Xenogears rejects the doctrines of his church once he learns of its sponsorship and purpose.
 * Xenosaga: Pellegri stops just short of accusing her superior, Margulis, of heresy when he questions the authority of Lord Heinlein.
 * On that note, Shion and Jin, who both are likely to have extensive ties to the Ormus religion - physically beat the crap out of The Pope at the end of Episode II.
 * Yuna becomes a heretic in Final Fantasy X when she resolves to reject the teachings of Bevelle and fight Sin to destruction.
 * Happens to quite a few people in that game, notably the Crusaders being excommunicated for their use of machina, despite their perfectly good intentions and their continued belief in Yevon.
 * Nero rejects the teachings of his church to save his lover, Kyrie, in Devil May Cry.
 * In Medieval II: Total War, regions where your faith isn't overwhelmingly dominant may spawn Heretics, or even convert a Priest you have stationed there to heresy. Since Heretics spread heresy and cause religious unrest, it's a good idea to have your Priests subject them to trials and burn them at the stake. If you're Catholic and you don't deal with Heretics, The Pope will send Inquisitors to your lands to start examining family members.
 * Byakuren Hijiri from Touhou, by the virtue of being compassionate to the Youkai. In this settings, the very presence of Celestial beings can harm Youkai regardless of either sides' morality.
 * Before that, there was Rikako Asakura, who was branded heretical for believing in science over magic.
 * In Mass Effect 2

Real Life

 * For Real Life examples, see Heresies and Heretics.

TV Tropes Will Ruin Your- Heresy!!!!! *BLAM*