What is the one role* your favorite actor or actress never should have accepted because it was so poorly matched for him/her?

I don't remember those but instead marvel at casting director's talent in choosing all the right people. How they get it so right so many times is an art unto itself.  I've always wanted to watch casting for a movie and how it all works from beginning to end. To me, those are real stars. 

Not so much the roles, but the entire movies.

Bruce Willis = Hudson Hawk

Bill Cosby = Leonard Part VI

Tom Selleck = Runaway

Since I have an ancestor who was a Hollywood actor, I will criticize him here ------- (Franchot Tone)  He looks like my grandmother in his early films when he was younger. This may not bother most, but it is kinda scary to me.