It's always dramatic when an anime character passes, but some demises are more excruciating than others. Whether the pain is physical or emotional, anime characters who died in cruel and unusual ways are harder to forget than those who go peacefully.
Some are horrible because the physical pain involved is so bad it defies imagination. One example of this is Zazan of Hunter x Hunter, who is burned alive by a miniature sun. Others are emotionally devastating, like when Maes Hughes of Fullmetal Alchemist is taken down by a homunculus who transformed into his beloved wife.
These scenes aren't for the squeamish - keep reading if you dare.
While fighting Mayuri, Szayel accidentally takes a drug that slows time to the point where a second lasts for a century. While this is happening, Mayuri takes the opportunity to explain the drug's effects while slowly stabbing Syazel. By the time it's over, Syazel has experienced hundreds of years worth of pain.
Maes Hughes is known for his passionate affection for his wife and young daughter, which is part of what makes his demise so upsetting. Not only do viewers know how powerfully impacted his loved ones will be, the homunculus who takes his life, Envy, transforms into his wife Gracia to make it that much more excruciating.
Kiyomi Takada is one of Light's loyal henchmen, and while she probably did deserve to be punished for her crimes, the way Light used her was pretty grisly. Using the Death Note, he forced her to set herself and some incriminating evidence on fire - all while she called out to him to help her.
Like most people in Parasyte, Nobuko Izumi's life comes to an end when her brain is taken over by a parasite. While this is painful, it's not exceptional. What is exceptional is that her body is used after her demise to nearly end her son Shinichi's life, and when the parasite living inside of her is finally killed, it's at Shinichi's hands.