Most humiliating roles of otherwise good actors

[Amenhotep Bakari-Sellers]

Electro and Jamie Foxx, the worse role he put on which ended up canceling Amazing Spiderman

[True Federalist (진정한 연방 주의자)]

I doubt anything could be more humiliating for Susan Hayward that appearing in the 1938 film Girls on Probation, starring Ronald Reagan, among others.

[Chancellor Tanterterg]

Jack Nicholson, Hoffa (1992)

One reviewer said Nicholson as a chunky boss missed the mark, and after seeing him in Cuckoo's Nest (1975) and The Shining (1980), I am inclined to agree.

Nicholson was great in Hoffa, he certainly gave a better performance than Al Pacino did in The Irishman.  Plus, while Hoffa wasn't a masterpiece or anything, it was still a solid film.

[Mexican Wolf]

I doubt anything could be more humiliating for Susan Hayward that appearing in the 1938 film Girls on Probation, starring Ronald Reagan, among others.

On the other hand, Girls on Probation probably didn't feature anyone in yellowface, right?

[I spent the winter writing songs about getting better]

Ben Affleck and Jennifer Lopez in Gigli used to be the canonical answer to this but everyone had forgotten that movie now.
Elizabeth Berkley basically destroyed her career with Showgirls.
The whole cast of Batman and Robin, especially Arnold Schwarzenegger and George Clooney. Also Chris O'Donnell basically destroyed his career with it and he's only in network TV crime dramas now.
Christina Ricci was a pretty well respected actress at the time "Bucky Larson: Born to be a Star" came out, and I was wondering why she agreed to star in such an obvious pile of sh!t then.
And of course the inexplicable star studded cast of this pile of sh!t: https://en.wikipedia.org/wiki/Movie_43

[True Federalist (진정한 연방 주의자)]

I doubt anything could be more humiliating for Susan Hayward that appearing in the 1938 film Girls on Probation, starring Ronald Reagan, among others.

On the other hand, Girls on Probation probably didn't feature anyone in yellowface, right?

You seem to be operating under the false impression that Howard Hughes spent much money on makeup. Other than maybe some fake facial hair, it's clear he didn't.

[Cassius]

Dirty Grandpa was pretty embarrassing for De Niro.

Of course the joke is on us given that for a lot of these movies (Patrick Stewart playing a sh**t in the Emoji Movie being a good example), the actor in question made it off with a fat sack of cash for not very much effort.

[MASHED POTATOES. VOTE!]

I think Al really needed that paycheck

[Devout Centrist]

Jacky Gleason in Smokey and the Bandit Part 3 was pretty embarrassing, especially since Burt Reynolds only made a cameo appearance.

[True Federalist (진정한 연방 주의자)]

I think Al really needed that paycheck

Perhaps he was hoping it would lead to a voice acting role in Tim Hortons Hears a Who.

[Landslide Lyndon]

Jeremy Irons in "Dungeons & Dragons" and "Eragon".