I was thinking about how some forms of science are more likely to be portrayed as evil than others, thinking that chemists really get a bad rap while astronomers are usually portrayed as good or neutral scientists. And then I thought, it seems to be that evil scientists are usually ones who make things or work with actual objects/people/animals. That's not to say that there aren't heroic scientists who do those types of things, as there often are, but I can't think of any evil scientists in fiction who are portrayed as doing merely theoretical work outside of someone whose theories are used to build something or create a substance (as in someone else does the grunt work). This is probably because of both the fear of "playing God" and also simply because a villain who can't do something concrete with his/her research (like creating poisons or machines) is harder to work into a plot unless the science is an incidental part of his/her character (like a villain who happens to like star-gazing). This would also be because exploding, bubbling poisons and doomsday machines are more visually exciting than a villain who does all his/her work on paper. Not to mention star-gazing is probably considered to be a humbling activity rather than something that would make someone do an Evil Laugh
out of pride for his/her creations.