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.
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.
Hellboy has its dark moments, but it's not unanimously regarded as the absolute darkest. The perception of darkness varies from reader to reader, and other comics might push the boundaries further in that aspect.