It depends on your perspective. Berserk is definitely dark, with its violent and tragic storylines. But some might argue there are other mangas that could be equally or even darker based on personal preferences.
In the '1984' novel, there are several significant deaths. Winston's spirit can be considered as 'dead' in a sense after his torture in Room 101. His transformation from a rebellious thinker to a broken shell shows a kind of death of the self. Another example is the disappearance of various people who oppose the Party, which implies their deaths. These deaths are not just physical but also symbolic of the totalitarian regime's power to crush individuality and freedom.
One of the most heartbreaking deaths in My Hero Academia fanfictions could be Deku's. Imagine if he sacrificed himself to save his friends in a really intense battle. His death would shatter the hearts of his classmates like Ochaco, who has feelings for him. It would also leave All Might feeling as if he failed to protect his successor.
Don't forget about fan - fiction websites. While they are mainly based on existing fictional universes, there are often some really good adventure stories with dark twists. For instance, in the Harry Potter fan - fiction realm, there might be stories that take the characters on a much darker adventure than in the original books.
There are some websites that offer free fantasy stories. For example, Wattpad has a wide variety of fantasy tales. You can search for 'darkest' - themed ones by using relevant keywords in the search bar. However, the quality may vary. Another option is to check out some free e - book platforms where independent authors might publish their dark fantasy works.
One of the darkest Marvel comics is 'The Punisher MAX'. It delves deep into the gritty and violent world of Frank Castle with very intense and disturbing storylines.
Well, for a manga to be the darkest, it often features a lot of hopelessness, a cruel and unforgiving world, and characters facing constant and overwhelming hardships. Also, the art style might contribute, with heavy use of shadows and dark colors.