novel - Making the antagonist

How do I make a really "good" antagonist? I like the Idea that they should have a motive, as in my novel, the current antagonist needs to inhabit earth so his race can prosper But what makes a really great story antagonist?

Answer

I suggest you to take a look at this great analysis of the Joker in "Batman the Dark Knight": https://youtu.be/pFUKeD3FJm8

Basically, these are the main elements:

1. the antagonist has a strong desire and intention, as much as the protagonist


2. this desire and intention are in conflict with the protagonist's ones. They are mutually exclusive: if you win, I lose. The world is literally "too small for both of us".


3. the antagonist makes leverage on the hero's weaknesses. They act as a relentless opposition to the hero, undoing all the hero's efforts.


4. they are strong, skilled, tough: they are the hardest obstacle ever faced. In a videogame, they would be "the boss": after easily defeating dozens of minions, the final fight is generally much harder, and likely to fail.


5. their actions question the very core of the protagonist's world view and values.


6. the antagonist has a strong logic: you can despise the motives, but you cannot disagree with the logic. You empathize with the antagonist, because you understand their reasons and nature, even if you don't like them.