One well - known 'evil powerful Harry Potter fanfiction' could be 'The Dark Lord Ascending'. It presents a very different take on Harry, where he succumbs to darker powers. However, such fanfictions often deviate from the original positive themes of the Harry Potter series.
I'm not really into promoting dark or evil fanfictions as they often deviate from the positive spirit of the original 'Harry Potter' series. However, some fanfiction platforms like FanFiction.net or Archive of Our Own might have such works, but you need to be cautious as the content might be disturbing or against the values of the original story.
One great 'Harry Potter' crossover fanfiction is 'Harry Potter and the Methods of Rationality'. It combines the magical world of Harry Potter with rational thinking and scientific concepts. It offers a fresh and thought - provoking take on the series, making Harry a more calculating and scientific - minded character, which is really interesting.
There's also 'Harry Potter and the Methods of Rationality'. It's a bit different but still has elements of a powerful and somewhat darker view. It shows Harry using his intelligence in a way that challenges the traditional magic world's norms, and there are some rather intense and thought - provoking plotlines.
One great independent Harry Potter fanfiction is 'The Changeling' which explores an alternate path for Harry where he has to face challenges in a more isolated and self - reliant way. It really shows his power growing in unique circumstances.
One great 'super powerful Harry Potter fanfiction' is 'The Life and Times of Severus Snape' by lilyseyes. It gives a deep and detailed look into Snape's life, which is really powerful as it shows a different side of this complex character from the books.
One great 'Harry Potter Rich and Powerful' fanfiction is 'The Heir of Slytherin's Ascension'. It portrays Harry in a very different light, where he discovers hidden powers and a vast inheritance. He uses his newfound wealth and strength to change the wizarding world for the better.
A frequent theme is the exploration of the dark side of magic. Since Harry has always been associated with the light side of magic in the original series, in these fanfictions, he delves into the darker, more forbidden aspects of magic. Also, there is often the theme of revenge. Harry might seek revenge on those who he feels have wronged him in the past, which leads him down an evil path. This is a big departure from the forgiving nature of the original Harry Potter character.
Some 'Harry Potter x Resident Evil' fanfictions are really creative. For example, in one story, the spells from Harry Potter are used to counteract the viruses in Resident Evil. The story might explore how Hermione's intelligence could be used to find solutions to the Resident Evil crises. Also, the Death Eaters could be compared to the evil corporations in Resident Evil, and how the heroes from both worlds could team up to fight against such great evils.
I'm not sure about a specific 'godlike harry potter evil dumbledore fanfiction' off the top of my head. But generally, in such fanfictions, the writer might rewrite the plot so that Dumbledore has been manipulating events all along for his own gain, and Harry, with his new 'godlike' powers, has to oppose him. You can try searching on fanfiction websites like Archive of Our Own or FanFiction.net.
A popular one is 'The Green Vial' which delves into the relationship between Harry and Draco. It's powerful because it shows their growth and how they come to understand each other in a different world than the original series.