I agree with many of the above posters that both words are too extreme for what the very human man really was. This question seems to be more about the mythology and legend that surrounds Columbus.
One side of the legend, that was taught in schools for years and was completely undisputed was that he "discovered" America. In this legend he is the hero of his time. He crossed the ocean knowing the world was round when everyone else thought it was flat. This is all untrue historically but was a common legend taught. In this version he is the hero.
The more current legend has Columbus as the leader of a genocide of Native Americans. He came here and brought violence and slavery and disease that wiped out whole popluations and was the beginning of the long history of terrible times for the native populations of the Americas. All the ills of the Native Americans are traced back to Columbus in this legend. Here he is unquestionably the villian.
The reality is both of these versions are more myth and legend than reality. What the real man set out to do and actually did is much more mundane and impartial than either of these popular mythologies present. He was not intentionally doing either of these things. The fact is the "villain" mythology is the more widely accepted right now, though the hero mythology existed for ages. Popularity at the present time doesn't make either true.