It's been some seventeen years since the death-filled Battle of Hogwarts that freed us from the reign of Voldemort—wait, nevermind, we don't live in Harry Potter World. Still, fans regularly observe the "anniversary," (among others) and author J.K. Rowling took a moment this year to apologize for the death of Fred Weasley.
In Harry Potter and the Deathly Hallows, (SPOILER but not really because that shit came out seven years ago) Weasley is killed in an explosion. It's especially tragic because, well, he's delightful, and also a twin. Though his death appeared in the 2007 book, the Battle of Hogwarts takes place in 1998, hence the seventeen years. Rowling also said that she will begin to apologize for one death a year after fans began asking about other beloved characters who were whacked. NEVER FORGET.
Correction: Percy Weasley survived the explosion during the battle of Hogwarts. Thanks, @pafifi!