Tom Riddle's Diary

• Type: Horcrux, Magical Diary
• Owners: Tom Marvolo Riddle, Lucius Malfoy, Ginny Weasley, Harry Potter
• Maker: Tom Marvolo Riddle

Tom Riddle's diary was a small, thin book with a plain black leather cover. On the back, the year “1943” was printed in peeling gold leaf. It appeared to be a common Muggle diary, having been purchased by a young Tom Riddle at a newsagent's shop on Vauxhall Road in London. When first opened, all of its pages were completely blank. However, it would not absorb ordinary ink if one tried to write in it. To interact with the diary, a person had to write on its pages, at which point their words would fade away and a response from the diary's memory would appear in its place.

As Lord Voldemort's first Horcrux, the diary contained a fragment of his soul, imbuing it with powerful and insidious Dark Magic. Its primary purpose was to preserve that piece of soul, granting its creator a form of immortality. The diary's key abilities included:

• Two-Way Communication: The diary could communicate with anyone who wrote in it. The memory of the sixteen-year-old Tom Riddle stored within its pages would engage the writer in conversation, manipulating them by appearing sympathetic and trustworthy.
• Possession: The diary could exert a powerful influence over the person who confided in it. By feeding on their fears, emotions, and secrets, it could gradually drain their life force and take control of their actions. This is how it forced Ginny Weasley to open the Chamber of Secrets and unleash the Basilisk.
• Memory Immersion: The diary was capable of pulling a person into its enchanted memories, allowing them to witness past events as if they were physically present. Harry Potter experienced this when the diary showed him a biased version of Riddle framing Rubeus Hagrid for the Chamber's previous opening.
• Life-Force Absorption: The ultimate goal of the soul fragment was to siphon enough life energy from its victim to create a corporeal form for itself. By the time Harry found Ginny in the Chamber, the memory of Riddle had almost fully manifested, while Ginny herself was close to death.

Tom Riddle created the diary as his first Horcrux in 1943, during his fifth year at Hogwarts. He used the murder of a fellow student, Myrtle Warren, to perform the spell that split his soul. Years later, before his first defeat, Lord Voldemort entrusted the diary to his loyal Death Eater, Lucius Malfoy. Voldemort informed him that the diary was a key to reopening the Chamber of Secrets but concealed its true nature as a Horcrux. In 1992, seeking to disgrace Arthur Weasley and purge Hogwarts of Muggle-borns, Lucius slipped the diary into Ginny Weasley's cauldron of second-hand books at Flourish and Blotts. Ginny began writing in the diary, and the memory of Riddle slowly possessed her, forcing her to reopen the Chamber and release the Basilisk. Horrified by its influence, Ginny attempted to discard it in a girls' bathroom, where it was later found by Harry Potter. Harry communicated with the diary and was manipulated into believing Hagrid was responsible for the attacks fifty years prior. After Ginny was taken into the Chamber, Harry discovered the truth. Inside the Chamber, he confronted the corporeal memory of Tom Riddle. After being fatally wounded by the Basilisk, Harry used a Basilisk fang he pulled from his arm to stab the diary. Basilisk venom is one of the few substances capable of destroying a Horcrux, and upon being stabbed, the diary bled thick black ink and the spectral form of Riddle screamed and vanished, destroying the soul fragment within.

Tom Riddle's diary is the central antagonistic force in Harry Potter and the Chamber of Secrets. It is the first Horcrux Harry encounters and destroys, although he is unaware of its true significance at the time. The diary's destruction provides Albus Dumbledore his first concrete proof that Voldemort may have created multiple Horcruxes, a theory that becomes central to the overarching plot of the series. The events surrounding the diary also serve to educate Harry about Voldemort's past and solidify his understanding of the insidious nature of Dark Magic.

• J.K. Rowling has stated that the idea for the diary was inspired by her younger sister's own diary and the “fear of someone reading your private thoughts” (J.K. Rowling interview). The magical diary represents a sinister manifestation of that fear.
• In the film adaptation of Harry Potter and the Chamber of Secrets, the destruction of the diary is depicted with a burning hole appearing through the book as Riddle's memory shatters into light (film).
• The film also shows Lucius Malfoy attempting to cast a curse on Harry in a Hogwarts corridor after Harry tricks him into freeing Dobby. This confrontation is an addition to the book's narrative (film).