For crimes against music, i would start with Schiff, Hewitt, Bang Bang and Lisitsa.
Not wholly disagreeing with the response to this but the thread's about whether you've wanted to murder a pianist; would you want to do this or would you rather have someone else do it and, if indeed the former, how would you go about it? Whack him/her over the head with the largest of your banjos?
I find Bang Bang not a musical criminal but a dull pianist with little to offer besides mild amusement at his physical clowining antics, although I do believe that he has other virtues. Lisitsa is again, to me, just a dull slightly more than competent pianist with whose performances I have never felt able to engage, but I'd not describe her as a musical criminal; indeed, I find the widespread adulation of her more offensive than her actual playing...
At least you haven't mentioned Marc-André Hamelin. And you've omitted reference to Martha Argerich who, fabulous as she is, has surely played Schumann's penny dreadful concerto more times than you have banjos...
Personally, if I felt that ill disposed towards a pianist, I'd opt for the rather less drastic and easier option of not listening to them.
Bestm
Alistair