Alien Conquistadors
Basically I'm looking for media where the world is invaded by aliens who want to Civilize humanity. They tell us they're here to save our souls, but what that winds up meaning is slave labor, forced conversions, torture, and executions. Bonus points if it covers Earth's later status as a colony to Space-Spain, and more bonus points if this is all tied to the Space-Doctrine of Discovery uniting Space-Europe under the Space-Pope
I know there have to be a few popular stories out there with premises like this, but I can't think of any, and I'd like to try some
it's not a 1-for-1 fit with what you're talking about, but your description gave me V vibes.
series trailer / promo
basically big ass spaceships show up one day "in peace" lead by a being who looks like Morena Baccarin with a very short haircut and a personal stylist that probably was poached from italian Vogue. the "visitors" claim they only need an insignificant amount of earth's resources and in exchange they will provide us with advanced technology to cure all disease and become a very advanced civilization. it turns out they are here to do something more akin to colonialism (enslavement, genocide, etc). and the series is about a few humans resisting and many humans collaborating (through naivety or morally bankrupt calculus), and the odd alien being like, "no wait, this is bad, actually" and joining the resistance.
i never watched it all, but i remember liking what i did see. i guess it was a remake of an earlier series, so there's a lot to the franchise if you deep dive all the media. it should be noted this was 2009, for regular TV, so the special effects are likely not going to have aged well.
i can tell you one thing....
if a powerful alien species showed up and their leader could appear like morena baccarin with short hair
spoiler
i'm selling out humans. adios muchachos! see you on the flip side of that big burger in the sky.
I was gonna say V as well. The original miniseries is WAY more explicit about this (and way better tbh).
also be glad that you didn't watch the entire remake because it had such a bullshit ending lol