I wouldn’t say the horribleness of a person is ever something that makes someone inseparable from their art. The art and the person just don’t necessitate each other. That said, I’m pretty sure someone might make a case for Nero, he burnt people on living candles and called it “art” and would lock people in concerts to hear him perform (if we assume the historical records are true). Relatedly, Saddam Hussein wrote a lot of fanfiction about defeating America with negative undertones that would make a Wattpad writer cringe.