Conor and Rousey for sure. And not without decent reason. Both prematurely celebrated as once-in-a-generation athletes, who thoroughly bought into their own hype, and were subsequently one-sidedly humbled.
What people forget though, is both are still incredible fighters.
Only 3 or 4 women have put together the win streak Rousey had, and the only one who comes close in spectacle is Nunes.
Conor blitzed through the fw rankings in about a year's time, to dethrone the fw GOAT in incredible fashion, then went up a weight class and took that belt too.