The most purely evil villains in all of Dragon Ball. I would have picked Frieza or Moro...

But Zamasu is the most evil for me. Unlike every other villain, he was supposed to be GOOD yet became evil due to being a delusional hypocrite. He committed genocide on his own kind, even killing his own mentor and destroyed Trunks' entire timeline. His belief he's doing the right thing doesn't make him less evil than the others, using your own ego as an excuse to do evil and commit genocide just makes you worse IMO.