We already talked about a protagonist profile- and we need a lot of the same kind of information on the antagonist. Remember that the antagonist can be a situation or an event or an idea instead of a person. That can make it harder to profile (and sometimes harder to create a background story).

However, be brave. Be creative. Face down that antagonist in any form it might take. You may have more than one in your story. For this exercise, choose one. But tomorrow's may focus on something else.
https://www.masterclass.com/articles/writing-101-protagonist-vs-antagonist-chara...

https://www.helpingwritersbecomeauthors.com/how-the-antagonist-functions-in-diff...

Most bad guys don't think of themselves as the bad guys. Allow that to be part of the way to make them at least a bit redeemable. One of my writing pet peeves is a bad guy with nothing to redeem him (Voldemort is an example). I appreciate the time and effort to make it seem like that bad guy has intentions and may even be trying to do the right thing from a certain point of view.

In the cross-purposes vein, sometimes all those people who are on the protagonist's side provide reasons to change and be different. Explore the gray area between all good and all evil and see what happens. Happy Writing!