In a new work I've started, I'm dealing wih more complex antagonist characters. I'm much more interested in writing stories with antagonists that have a strong moral compass, than villains that are simply behaving badly and know it the whole time. While there are certainly times when outright villiainy is useful in a storyline, an antagonist with a moral compass may generate sympathy and, therefore, more reader involvement in the central conflict of a story.
For clarity, I like the distinction made in Eventide Unmasked, a blog by Hayle Lavik at -
The key terms in the article are defined as "villains are the people who know they're doing bad, while antagonists hold a strong conviction in the rightness of their own (potentially horrible) actions." While there is more to it, I like the simplicity of this distinction.
There are some great sources available on various antagonists. The site tvtropes.org offers "A Sliding Scale of Antagonist Vileness" -
The variations range from those that are merely bumbling antagonists to villains well beyond the "Moral Event Horizon" of perceived redeemability.
When writing, I find dealing with a moral antagonist is more challenging that a simple bad villain. The moral view of such antagonists has to be kept consistent even when it differs from any other characters in a work.
Even villians can sometimes have some moral convictions. Consider Nurse Ratched in "One Flew Over the Cuckoo's Nest." She seeks to maintain order in an asylum with her unique kind of moral code. Such antagonists are among the most memorable of all villains in storytelling.
- A strong antagonist helps to make an entire work more memorable.