For 50 years, the hard-working teens (and dog) of Mystery, Inc. have been investigating the paranormal—and inspiring some wild fan theories.
Conspiracy theories and pot brownies: the secret history of Scooby-Doo
Scooby-Doo' Fan Theories
Scooby-Doo's Velma is actually queer (and always has been)
Scooby-Doo: The Hidden TRUTH Behind Scooby - Secrets & Theories
Scooby-Doo' wasn't just another cartoon. It was a reaction to the political turmoil at the time
The House with a Clock in Its Walls සිංහල Movie Review, Ending Explained Sinhala
Weird Fan Theories Have Kept 'Scooby-Doo' Going for 50 Years
CONSPIRACY THEORY: AUSTRALIA IS SCOOBY DOO, Scooby-Doo
Not sure if this has been done already but made an Iceberg of Scooby Doo fan theories : r/Scoobydoo