Tom Riddle's Diary


Tom Riddle used his diary to create his next Horcrux during his sixth year at Hogwarts. He cast the spell after murdering his fellow student Moaning Myrtle using a Basilisk. The diary is introduced in the fourth chapter of the Chamber of Secrets and is destroyed by Harry Potter during the climax of the same book. Before Voldemort's downfall, he entrusted the Horcrux to Lucius Malfoy. While aware of its corrupting magical properties, Malfoy did not know the diary was a Horcrux. In an attempt to discredit Arthur Weasley, Malfoy hid the diary in Ginny Weasley's cauldron, amidst her other books. Tom Riddle's soul-fragment possessed Ginny and through her reopened the Chamber of Secrets. At the end of book two, Harry saved Ginny and destroyed the diary by stabbing it with the venomous fang of a Basilisk, making it the first Horcrux to be destroyed. His reports of the diary's behavior to Dumbledore were the latter's first inkling that Voldemort might have created, not just one Horcrux, but several: "What intrigued and alarmed me most was that the diary had been intended as a weapon as much as a safeguard[1," implying that Voldemort must have had backups of some sort.
To Rowling, a diary is a very scary object. She said in an interview that "the temptation particularly for a young girl, [is] to pour out her heart to a diary." Rowling's little sister Diane was prone to this, and her great fear was that someone would read her diary. This gave Rowling the idea to have a diary that is, in itself, against the confider. When asked what would have happened if Ginny had died and Riddle had managed to escape, Rowling declined to give a straight answer, but revealed that "it would have strengthened the present-day Voldemort considerably."