MatPat, AKA GameTheory. He’s kind of an old school YouTuber that made videos theorizing video games. He’d combine real world science and game lore to try to come up with theories. Some of his theories were plausible but others were very far fetched or even downright silly, but it was all in good fun. His Five Nights At Freddy’s theories got really big and were fairly foundational in the early days.