21 April is the 111th day of the year (112th in leap years). There are 254 days remaining until the end of the year.
- [[1920s|1926]]: Elizabeth Windsor, Queen of England in the 1990s, is born.
- 1996: Cornelius Fudge passes Educational Decree Number Twenty-Eight, making Dolores Umbridge Headmistress of Hogwarts School of Witchcraft and Wizardry.
- 1997: Harry Potter, Draco Malfoy, and Ernie Macmillan attend Potions class whilst all other students currently of age take their Apparition tests, which Ron Weasley fails. Aragog's funeral takes place. Harry Potter uses Felix Felicis to obtain the Horcrux memory from Professor Slughorn among other lucky events.
- 1998: Harry Potter, Ron Weasley, and Hermione Granger — amongst others — stay at Shell Cottage and prepare to break into the Lestrange Vault in Gringotts Wizarding Bank.
Behind the scenes
- 1991: Frank Dillane, the actor, who plays a 16-years old Tom Riddle in the film adaptation of Harry Potter and the Half-Blood Prince, is born.