Seer

A Seer is a witch or wizard who possesses the rare, innate magical ability to see into the future. This gift of foresight is often referred to as The Inner Eye. True Seeing is a specific and powerful form of Divination, distinct from the learned arts like tasseomancy (reading tea leaves) or crystallomancy (crystal ball gazing), which many practitioners of Divination use with little to no success. The ability to See is exceptionally rare. Professor Minerva McGonagall noted that a true Seer is only born once in a great while, which was the basis for her considerable skepticism towards Divination as a subject taught at Hogwarts School of Witchcraft and Wizardry. When a Seer makes a genuine Prophecy, they typically enter an involuntary, trance-like state. Their voice and demeanor may change, and they are usually unaware of what they have said afterward. Professor Sybill Trelawney, for example, spoke her prophecies in a harsh, altered voice and had no memory of them upon returning to consciousness.

• Cassandra Trelawney: A celebrated and famous Seer from the past. She was the great-great-grandmother of Sybill Trelawney, and her reputation was a factor in Albus Dumbledore agreeing to interview her descendant.
• Sybill Trelawney: The Divination professor at Hogwarts School of Witchcraft and Wizardry during Harry Potter's time. Despite her theatrical personality and a tendency to make vague, gloomy, and often inaccurate predictions in her classes, she is a true Seer. She is known to have made at least two genuine prophecies of immense importance to the Second Wizarding War.

A true Prophecy made by a Seer can be magically recorded in a small, smoky glass orb. These records are meticulously labeled and stored in the Hall of Prophecy, a vast chamber within the Department of Mysteries at the Ministry of Magic. Each Prophecy orb is magically protected so that it can only be retrieved from its shelf by the person or people about whom it was made. The concept of prophecy is central to the entire narrative of the Harry Potter series:

• The First Prophecy: Made by Sybill Trelawney to Albus Dumbledore at the Hog's Head Inn, it foretold the birth of one with the power to vanquish Lord Voldemort. Partially overheard by Severus Snape, this Prophecy led Lord Voldemort to target the Potter Family, resulting in the murder of James Potter and Lily Potter and the scarring of Harry Potter, which ultimately set the entire story in motion.
• The Second Prophecy: Made by Sybill Trelawney to Harry Potter near the end of his third year, it foretold the return of a faithful servant to Lord Voldemort, which would enable his master to rise again. This Prophecy was fulfilled when Peter Pettigrew escaped and rejoined the disembodied Lord Voldemort.

As Albus Dumbledore later explained to Harry Potter, a Prophecy does not guarantee an outcome. He stressed that it is the choices made by individuals in response to a Prophecy that give it power. Lord Voldemort's choice to act on the first Prophecy was what “marked” Harry Potter as his equal.

The word “seer” is an English term that literally means “one who sees.” It is derived from the verb “to see” and is commonly used to refer to a person with prophetic or clairvoyant abilities.

• In the film adaptation of Harry Potter and the Prisoner of Azkaban, Sybill Trelawney's trance is depicted with her body convulsing and her voice becoming deep and raspy, visually emphasizing the involuntary and otherworldly nature of the Prophecy. (film)
• J.K. Rowling has stated that while other magical beings like Centaurs can also read the future, their methods (such as astrology by observing the planets) are distinct from the innate, spontaneous gift possessed by a human Seer. (Pottermore)