Maxperson
Morkus from Orkus
I wouldn't find that objectionable. Bards, Clerics, Paladins, Sorcerers, and Warlocks would finally have a good use for the other half of their starting saves!First thing that comes to mind is monsters with abilities that negate player agency. Now, there are few of them in MM. But homebrew one with innate dominate person that targets cha save, that one would be very nasty.

