Part of the mystery is figuring exactly which characters ARE antagonists though...
In Digital Cowboy, there are a lot of factions at work, some allied, some opposed, some only aware of the MC when he gets involved in their affairs... At least one is a lot like Skynet - but so is his main ally...
In book one of Strange Awakening, there are a bunch of shifting antagonists, but the main one is Lord Mordent. In book two, it will mainly be Baron Vel'Ziar and his Biomechs.
In Between Worlds the enemy is, ultimately, a prophecy and an ancient evil that doesn't show up until the middle or end of the second book. But there are a lot of little antagonists throughout.
In True Blue... well, there will be a main antagonist for a while but he doesn't exist yet where I left off writing - and each story also has its own antagonist - either super-powered criminals or weird scientists so far.
Jack Diamond has a band of Lovecraftian monsters called demons, led by one named "Morgalis, the Wizard" that are involved in all levels of criminal activity and general support of vices and just nastiness.
So, so far, everything BUT Living Ideologies, MC's alter ego, historical figures, and World Order (but could only pick six)
If I ever get anywhere with Assassin King, that will add in World Order (or, perhaps more accurately, LACK of World Order) as the ultimate foe but there are a lot of lesser ones on the path.