Does a mindless antagonist have a personality?
Question: The Main Antagonist is an undead creature known as a Lich. He is a mindless entity that has only one goal: to destroy every soul in the world. He is a creature used by a bigger entity know simply as The Darkness. If The Lich is mindless, how would you attempt to describe his personality? Also, if he is just a pawn for The Darkness, yet he is the one combating the good guys, is he the main antagonist or is that spot filled by The Darkness?
The character you're describing sounds much like a force of nature -- like Moby Dick, or the fish in The Old Man and the Sea
. Neither of these examples has much personality to speak of.
Basically, this type of character takes on the dramatic role of avoiding or preventing the story goal, which is typical of an antagonist.
Of course, an archetyal antagonist would also have the function of persuading characters to reconsider their efforts, which this character cannot do. You may want to create a human character who can argue that position.
You can also decide to give the Lich a personality, if it serves the interests of the story. In Man vs Nature stories, the force of nature often has no personality because the message concerns the pointlessness of humans struggling against inhuman power. If that's not the message you want to convey, consider humanizing the Lich by giving it a personality and letting your hero argue with it.
Is the Lich the "main antagonist"? That's up to you. Perhaps what you're envisioning is a bit like Governor Tarkin in Star Wars
who stands in for the Emperor in Episode IV. The Lich could be a stand-in for the Darkness, taking on his role until the Lich is no longer needed.