Professor Septima Vector

Professor Septima Vector is the witch who serves as the Professor of Arithmancy at Hogwarts School of Witchcraft and Wizardry during Harry Potter's time at the school. A character mentioned only by name and reputation, she is known for teaching a highly complex and demanding magical discipline. Her most notable student is Hermione Granger, who excels in the subject. Professor Vector represents the academic rigor present at Hogwarts, particularly in magical fields that require intellectual dedication over practical spell-casting.

Professor Vector's life before or after her tenure at Hogwarts is not detailed in the novels. Her presence in the story is established during the 1993-1994 school year, when Hermione Granger begins taking Arithmancy in her third year. The subject is immediately established as highly difficult, requiring the use of complicated number charts. She continues to teach Hermione through her O.W.L. and N.E.W.T. years. By the 1996-1997 school year, Professor Vector is known for assigning a significant amount of challenging homework, as Hermione complains that a “nit-picky” essay for Arithmancy is preventing her from helping Ron Weasley with his own assignments. Professor Vector's presence at the school during the Battle of Hogwarts is unconfirmed, though it is likely she participated in the school's defence alongside her colleagues.

Professor Vector's physical appearance is never described in the seven canonical novels. Based on the nature of her subject and her students' reactions, her personality can be inferred. She is presumed to be highly intelligent, logical, and methodical. The complexity of Arithmancy suggests she is a very demanding and strict teacher who holds her students to a high academic standard. Her reputation for assigning “nit-picky” essays and copious amounts of difficult homework reinforces this perception.

• Arithmancy Expert: As the Professor of Arithmancy, Professor Vector is an undisputed expert in this field. Arithmancy is a branch of magic concerned with the magical properties of numbers, and it is used as a form of divination to predict the future. Her mastery of this subject implies a sharp, analytical mind.
• General Magical Proficiency: To hold a teaching position at Hogwarts, Professor Vector is undoubtedly a skilled and knowledgeable witch, proficient in a wide range of general magic.

No specific possessions of Professor Vector are mentioned in the books, although she would have certainly owned a wand.

Professor Vector's primary relationship detailed in the series is with her student, Hermione Granger. Hermione is one of the few students shown to have both the aptitude and the interest for Arithmancy, and she continues the subject to the N.E.W.T. level. While no direct conversations are recorded, Hermione's dedication implies a level of academic respect for her professor. Her relationship with other students, such as Harry Potter and Ron Weasley, is non-existent, as they found the subject baffling and opted not to take it.

• Septima: This name is derived from the Latin word septimus, meaning “seventh.” The number seven is considered the most powerfully magical number in the wizarding world, making this name highly appropriate for a professor of a number-based magical art.
• Vector: In mathematics and physics, a vector is a quantity that has both magnitude and direction. This scientific and mathematical term directly relates to the logical and precise nature of Arithmancy.

• In the film adaptation of Harry Potter and the Chamber of Secrets, an unnamed teacher, often identified by fans as Professor Vector, is seen at the staff table. This character was played by actress Hazel Douglas (film).
• Professor Vector appears as a character in the Harry Potter and the Order of the Phoenix video game, where she gives Harry a quest to find five hidden numbers, promising a reward from her “secret store” (video game).
• According to the official Wizarding World website, Arithmancy was Professor Albus Dumbledore's favourite subject when he was a student (Pottermore).