"Dumbledore is Ron From the Future" is the Wildest Theory Harry Potter Fandom Ever Produced
This fan theory was so crazy that even J.K. Rowling came to Twitter to debunk it.
There are dozens of crazy Harry Potter fan theories out there from icky "cannibalism being part of the creating-a-Horcrux ritual" to Rowling-approved "Dumbledore is Death in The Tale of Three Brothers."
After all this time, fans don't get tired of creating and discussing various theories about the beloved book and film series. While actively interacting with fans, J.K. Rowling rarely addresses any of those speculations. However, some of them turned out to be so crazy that the author just had to disprove them.
Probably the wildest fan theory out there was once posted on Harry Potter's Page discussion thread; it states that Dumbledore is actually Ron Weasley from the future. As crazy as it sounds, at the time of its creation (between the publication of The Order of the Phoenix and The Half-Blood Prince) the theory sounded so convincing that it took a tweet from Rowling to debunk it. The author of the theory based it on facts from the first five books of the series.
The author noted that Ron and Dumbledore are very much alike. They are both described as tall and thin, with long noses and hands. Besides, they both have red hair. Though Dumbledore is famous for his silver hair and beard, his younger version was described as having "auburn" hair in a scene where he meets Tom Riddle.
Secondly, there's Bertie Bott's Bean.
Dumbledore tells Harry that he doesn't eat those because in his youth he got a particularly disgusting vomit-flavored one. But the canon states that Bertie Bott was born when Dumbledore was over 90 years old. More than that, both Ron and Dumbledore seem to be obsessed with different types of World of Wizarding candy. After all, it was Ron who helped Harry figure out that Dumbledore's password was Cockroach Clusters.
Furthermore, there is a thing about Dumbledore and socks. The author of the theory points out that Ron often gets socks from his mother but usually doesn't appreciate the gift. And when Harry asks Dumbledore what he sees in the Mirror of Erised, the wizard replies he sees himself holding a pair of socks. Add to that the hate for the color maroon, purple robes, the ability to know things that Dumbledore shouldn't, and some other things and the theory starts to sound pretty convincing.
The Deathly Hallows completely debunked this theory. But even before that, J.K. Rowling did it herself by simply writing "False Theory" on Twitter.