Ernie Macmillan

Ernest “Ernie” Macmillan was a Pure-blood wizard and a student at Hogwarts School of Witchcraft and Wizardry in the same year as Harry Potter. Sorted into Hufflepuff house, Ernie was known for his somewhat pompous but ultimately loyal and brave nature. He served as a Hufflepuff Prefect and was a dedicated member of Dumbledore's Army. Though initially suspicious of Harry Potter, he evolved into a staunch ally, representing a segment of the Hogwarts student body whose opinion shifted in Harry's favor. He fought bravely in the Battle of Hogwarts, demonstrating his unwavering loyalty to his friends and his school.

Ernie's time at Hogwarts was marked by his evolving relationship with Harry Potter.

• Second Year: During the crisis involving the opening of the Chamber of Secrets, Ernie became a vocal proponent of the theory that Harry was the Heir of Slytherin. His suspicion intensified after his close friend, Justin Finch-Fletchley, was found Petrified near a seemingly threatening Harry. Ernie publicly declared his fears, though he stated he hoped Harry wouldn't attack him because his family was Pure-blood for nine generations. After Hermione Granger was also petrified, Ernie realized his error and offered Harry a full and public apology, demonstrating his capacity for reason and fairness.
• Fourth Year: Ernie was a fervent supporter of the Hogwarts Champion, Cedric Diggory, during the Triwizard Tournament. He wore a magical badge that read “Support CEDRIC DIGGORY” and flashed the message “POTTER STINKS,” believing Harry had cheated his way into the competition. His opinion began to soften after Harry performed exceptionally well in the First Task, and he was among the first to start speaking to Harry again.
• Fifth Year: Following Lord Voldemort's return, Ernie was one of the few students who believed Harry and Albus Dumbledore from the very beginning. He loudly defended Harry in public, even in the Hogwarts Express carriage. He and Hannah Abbott were made Hufflepuff Prefects. A serious student, he was often seen discussing his study schedule for the upcoming O.W.L.s. He eagerly joined Dumbledore's Army to learn practical defence and was a committed member.
• Sixth Year: Ernie continued his studies into the N.E.W.T. level, taking challenging subjects like Potions with Professor Horace Slughorn. He remained part of the reformed Dumbledore's Army.
• Seventh Year: Ernie returned to Hogwarts under the brutal regime of the Carrows. When Harry Potter returned to the castle, Ernie helped rally the members of Dumbledore's Army and chose to stay and fight in the Battle of Hogwarts. He was instrumental in organizing the evacuation of younger students before joining the battle. During the fighting, he, Luna Lovegood, and Seamus Finnigan saved Harry, Ron Weasley, and Hermione Granger from a horde of Dementors by casting their respective Patronuses.

Ernie is described in the novels as a “stout boy.” He carried himself with an air of importance and could be pompous and officious, particularly in his early years. He was quick to jump to conclusions, but also quick to admit when he was wrong. Fundamentally, Ernie was just, brave, and exceptionally loyal, embodying the key traits of Hufflepuff house. He took his responsibilities as a Prefect and his studies very seriously. His loyalty to his friends, such as Justin Finch-Fletchley, and his unwavering belief in Harry Potter and Albus Dumbledore in his later years showcased his strong moral character. His bravery was proven beyond doubt when he fought valiantly in the Battle of Hogwarts.

• Patronus Charm: Ernie was a skilled enough Wizard to cast a corporeal Patronus. His Patronus took the form of a boar. He used this powerful charm to help drive away a large number of Dementors during the Battle of Hogwarts.
• Defensive Magic: As a dedicated member of Dumbledore's Army, Ernie learned and practiced a variety of defensive and offensive spells. His ability to fight in the Battle of Hogwarts suggests he was a competent duelist.
• General Magical Aptitude: Ernie was a hard-working student who achieved the high O.W.L. grades necessary to advance to N.E.W.T.-level classes in difficult subjects like Potions, demonstrating his academic competence.

• Wand: The specifics of Ernie's Wand (core, wood, and length) are unknown.
• Magical Badge: In his fourth year, he owned a magical badge enchanted to show support for Cedric Diggory and disdain for Harry Potter.

• Harry Potter: Ernie's relationship with Harry was a journey from antagonist to ally. He began as a key source of the “Heir of Slytherin” rumors but grew to become one of Harry's most vocal supporters within Hogwarts, eventually fighting alongside him as a brother-in-arms.
• Justin Finch-Fletchley and Hannah Abbott: Ernie was very close with his fellow Hufflepuffs. His fear for Justin's safety drove his actions in their second year, and he and Hannah were often seen together, becoming Prefects at the same time and studying for their O.W.L.s together.
• Dumbledore's Army: Ernie was a loyal member, believing in the group's purpose and its leader from the start.

• Ernest: The name is derived from the German word ernst, meaning “serious, resolute, or earnest.” This perfectly reflects Ernie's personality, as he is a very serious student who is resolute in his beliefs and loyalties.
• Macmillan: This is a well-known Scottish surname derived from the Gaelic MacMhaolain, meaning “son of the tonsured one” or “son of the devotee.” The name's historical roots suit Ernie's proud declaration of his nine-generation Pure-blood lineage and his devotion to his house and his cause.

• In the film adaptations of the Harry Potter series, Ernie Macmillan is portrayed by actor Louis Doyle.
• J.K. Rowling revealed on her former website that Ernie Macmillan was one of the “Original Forty,” the first group of students from Harry's year she created before the first book was written. (J.K. Rowling official website)