Just to throw in some thoughts. A human antagonist will almost always believe they are doing the right thing. However, they don’t need to be sympathetic for it. There are many examples in history of people that were downright vile doing what they thought was a good thing. Beliefs of superiority due to race, gender, sexuality, religion, etc. have led to many atrocities that were supposed to be for the right reason. While some of these people are universally hated, some are heroes or villains depending on who you ask. Winston Churchill for example. Often seen as a hero by the media, but I’m sure the Irish and Indians have much different views on him. Or Sir John A. MacDonald. One of the leading figures in the formation of Canada as a nation and the first Prime Minister. However an alcoholic and involved pretty firmly in the Residential Schools.
If not human though, minds work in different ways. A few examples have been brought up such as Jaws, or the Raptors in Jurassic Park. These though are primal creatures acting on instinct. Slasher villains such as Jason Vorhees or Michael Myers are often supposed to be embodiment of evil but they are really mostly instinctual and primal. Characters like Pinhead from Hellraiser though have objectives and goals though they are clearly not of the moral variety.
My current story my villain is a demon. He has plots and schemes that involve the destruction of many lives in one way or another, and he’s not sympathetic to the pain he causes as that stands in his way. However, he just just go off destroying things for the shits and giggles of it. It’s less evil, and more amoral from common society’s standpoint.