Hubris (/ˈhjuːbrɪs/ from ancient Greek ὕβρις) describes a personality quality of extreme or foolish pride or dangerous overconfidence, often in combination with (or synonymous with) arrogance. In its ancient Greek context, it typically describes behavior that defies the norms of behavior or challenges the gods, and which in turn brings about the downfall, or nemesis, of the perpetrator of hubris.
The adjectival form of the noun hubris is "hubristic". Hubris is usually perceived as a characteristic of an individual rather than a group, although the group the offender belongs to may suffer collateral consequences from the wrongful act. Hubris often indicates a loss of contact with reality and an overestimation of one's own competence, accomplishments or capabilities.
In ancient Greek, hubris referred to actions that shamed and humiliated the victim for the pleasure or gratification of the abuser. The term had a strong sexual connotation, and the shame reflected upon the perpetrator as well.
Violations of the law against hubris included what might today be termed assault and battery; sexual crimes; or the theft of public or sacred property. Two well-known cases are found in the speeches of Demosthenes, a prominent statesman and orator in ancient Greece. These two examples occurred when first Midias punched Demosthenes in the face in the theatre (Against Midias), and second when (in Against Conon) a defendant allegedly assaulted a man and crowed over the victim. Yet another example of hubris appears in Aeschines' Against Timarchus, where the defendant, Timarchus, is accused of breaking the law of hubris by submitting himself to prostitution and anal intercourse. Aeschines brought this suit against Timarchus to bar him from the rights of political office and his case succeeded.
In ancient Athens, hubris was defined as the use of violence to shame the victim (this sense of hubris could also characterize rape). Aristotle defined hubris as shaming the victim, not because of anything that happened to the committer or might happen to the committer, but merely for that committer's own gratification:
to cause shame to the victim, not in order that anything may happen to you, nor because anything has happened to you, but merely for your own gratification. Hubris is not the requital of past injuries; this is revenge. As for the pleasure in hubris, its cause is this: naive men think that by ill-treating others they make their own superiority the greater.
Crucial to this definition are the ancient Greek concepts of honour (τιμή, timē) and shame (αἰδώς, aidōs). The concept of honour included not only the exaltation of the one receiving honour, but also the shaming of the one overcome by the act of hubris. This concept of honour is akin to a zero-sum game. Rush Rehm simplifies this definition of hubris to the contemporary concept of "insolence, contempt, and excessive violence".
The Greek word for sin, hamartia (ἁμαρτία), originally meant "error" in the ancient dialect, and so poets like Hesiod and Aeschylus used the word "hubris" to describe transgressions against the gods.  A common way that hubris was committed was when a mortal claimed to be better than a god in a particular skill or attribute. Claims like these were rarely left unpunished, and so Arachne, a talented young weaver, was transformed into a spider when she said that her skills exceeded those of the goddess Athena. Additional examples include Icarus, Phaethon, Salmoneus, Niobe, Cassiopeia, and Tereus.
These events were not limited to myth, and certain figures in history were considered to be have been punished for committing hubris through their arrogance. One such person was king Xerxes as portrayed in Aeschylus's play The Persians, and who allegedly threw chains to bind the Hellespont sea as punishment for daring to destroy his fleet.
What is common to all these examples is the breaching of limits, as the Greeks believed that the Fates (Μοῖραι) had assigned each being with a particular area of freedom, an area that even the gods could not breach. 
The word hubris as used in the New Testament parallels the Hebrew word pasha, meaning transgression. It represents a sense of false pride that makes a man defy God, sometimes to the degree that he considers himself an equal. In contrast to this, the common word for sin was hamartia, which refers to an error and reflects the complexity of the human condition. Its result is guilt rather than direct punishment as in the case of hubris .
In its modern usage, hubris denotes overconfident pride combined with arrogance. Hubris is often associated with a lack of humility. Sometimes a person's hubris is also associated with ignorance. The accusation of hubris often implies that suffering or punishment will follow, similar to the occasional pairing of hubris and nemesis in Greek mythology. The proverb "pride goeth (goes) before destruction, a haughty spirit before a fall" (from the biblical Book of Proverbs, 16:18) is thought to sum up the modern use of hubris. Hubris is also referred to as "pride that blinds" because it often causes a committer of hubris to act in foolish ways that belie common sense. In other words, the modern definition may be thought of as, "that pride that goes just before the fall."
Examples of hubris are often found in literature, most famously in John Milton's Paradise Lost, in which Lucifer attempts to compel the other angels to worship him, is cast into hell by God and the innocent angels, and proclaims: "Better to reign in hell than serve in heaven." Victor in Mary Shelley's Frankenstein manifests hubris in his attempt to become a great scientist; he creates life through technological means, but comes to regret his project. Marlowe's play Doctor Faustus portrays the eponymous character as a scholar whose arrogance and pride compel him to sign a deal with the Devil, and retain his haughtiness until his death and damnation, despite the fact that he could easily have repented had he chosen to do so.
An example in pop culture is the comic book hero Doctor Strange, wherein highly talented and arrogant neurosurgeon Dr. Stephen Strange is involved in a vehicular accident. Unlike the Greek figures Salmoneus, Icarus and Phaethon, he survives, though his hands are severely damaged, and thus his career as a neurosurgeon are shattered. After western medicine fails to help him, he seeks healing in the mystic arts, and though he never fully recovers, he becomes a powerful sorcerer.
A historical example of hubris was furnished by General George Armstrong Custer in the decisions that culminated in the Battle of Little Big Horn; Custer is apocryphally quoted as having exclaimed: "Where did all those damned Indians come from?"
C. S. Lewis wrote in Mere Christianity that pride is the "anti-God" state, the position in which the ego and the self are directly opposed to God: "Unchastity, anger, greed, drunkenness, and all that, are mere fleabites in comparison: it was through Pride that the devil became the devil: Pride leads to every other vice: it is the complete anti-God state of mind."