I was gonna mention this since it is so obviously the GOAT heel turn but I was sticking with strictly WWF/E examples only. I love how Hogan gave his heel promo where he explained himself right then and there instead of just waiting the next night to do it. I also love the visual of the ring brimming with garbage while he spoke. And while it's unfortunately been edited off almost all video clips of BATB '96, some fan actually jumped over the guardrail and tried to go after Hogan in mark rage too, but security pulled him out. They should have left that part in, it makes the moment feel even more real and awesome.
I also agree with anyone who says that Austin's heel turn was Blue. The moment and idea itself was kind of awesome but Austin was still a red hot babyface and the whole thing just leaves a bad taste in your mouth when you know how disappointing his heel run was afterwards. They could have booked the same exact match with Austin pummeling The Rock with a steel chair like twenty times without adding in Vince's involvement. The WM X-7 ending would be more epic to look back on nowadays.