10. Ralph Bohner
WandaVision is a gem of a series that may well be Marvel's greatest accomplishment ever. But even the Emmy-winning series divided audiences from time-to-time, and nothing divided them more than Mr. Ralph Bohner.
Hear me out, because I was there, too: I saw the response. I was part of it. Seeing Evan Peters in the MCU was a delight. Seeing him back as Pietro, playing on the fact that he played the role of Quiksilver in Fox's X-Men saga, was a thrill. Revealing that it was too good to be true was a blow, but a necessary one that added to the drama. The show needed to highlight Agatha Harkness as an all-powerful threat and it did. But naming him Ralph Bohner... that wasn't so great.
Look, it was always going to be a tough pill to swallow if Peters' character wasn't who he said he was, but that wasn't the issue. The fact that Marvel's first potential foray into the multiverse (at the very beginning of The Multiverse Saga) was actually just an opportunity to make an unfunny innuendo that felt like it belonged in a 2000s teen movie - which wasn't exactly the style WandaVision was going for. That's what really divided audiences.hhhh
Whatever, it's far from the worst offense in the MCU. Quicksilver never was and Ralph came and went. But this was below WandaVision and fans haven't really been able to let it go because of that.