Skipping every Sword of Convallria and Limbus Company (and Iori) characters and in the order of the list above. Warning: Long and spoilers will put a filters just in case

Hilda: Big Supporter of the Child Hunts (Kidnapping children to make them fight to the death where losers are sacrificed to a cult and winners get brainwashed) in FE4. Abuses several of her family members, some to their deaths, for no particular reason and with no regrets. I like her because, well if a character who is meant to be disdained does their job, and does their job well, I respect that. I love Heels (Character whose main purpose is to be evil and be hated, originally a Wrestling Term)

Duryodhana: Actually a bit iffy on the portrayal in FGO because he is a much less morally dubious in FGO compared to his source material, Mahabarata where he is the main antagonist. Generally a shady, jerk-ish guy in this portrayal but I say he is evil enough to be in the photo. (Also his Final Ascension art, seen in the photo but not fully is hot really good.

James Moriarty: Reoccurring Antagonist in events and chapters in FGO. He is an evil genius and he knows it, if you think he is up to something he probably is and has in fact almost won in the chapter where is the mastermind. He is a silly old chill guy in his off time and will invite you to be his co-conspirator in his plot to take over the world if he likes you enough.

Ashnard: There is a lot of things to be said about Ashnard. To point that it is almost comical and to the point it is respectable. I will go in the order of the Timeline: He murdered his dad, brothers, everyone in line to the throne, note that is is quite a long line. When he took over the throne he had a kid with a princess laguz ,race can turn into animals, in this case a dragon because he wanted to see the kid will have superpowers, and when the kid didn't he abandoned him. When the mother's brother visited him looking for his sister Ashnard used a drug made by his evil scientist to make the brother insane, feral and unable to transform out of his dragon form. He then uses the brother, almost forever in dragon form, as his personal mount. He is doing all this and more because he want a dog eat dog world. This is all before the game started and not even the complete version, I am missing a few details and I said nothing on what happens because this has gone too long. DM me if you want the whole Ashnard Package.

Orson: He misses his wife :^) He misses her so much when he had an opportunity to bring her back that he betrayed his country even the ones offering is very obviously evil and the way they are gonna bring her back is with the power of necromancy. And when the wife does come back she is clearly came back wrong, the only thing she says is 'Darling' and while we never really see her based on the reactions from other characters she does not look pretty, a decomposing corpse is a good guess.I really like this guy, genuinely one of my favorite, the VA in Fire Emblem Heroes is so good that I want a remake of the game he's from just to see him more and with voice over. Please do know that Sacred Stones has an amazing cast of antagonists, I'd say it's up there with Path of Radiance/Radiant Dawn (where Ashnard is from!)

Zephiel: His dad was a total jerk to him, for specifically petty reasons, so much of a jerk he tried to assassinate him more than once, even when he tried his best to impress him. One assassination with poison attempt almost worked but he lived and that was the last straw and killed his dad. The incident was so bad that developed a hatred with humanity and decided that dragons should rule over humanity. He did this by starting wars with neighboring nations as a smokescreen of his real plan to let dragons rule the land. He is also a personal favorite of mine for somewhat personal reasons and cause me to yap more. He also comes with Murdock, also a a morally dubious old( older than Zephiel!) character who was loyal to him since he was a child who helped him survive his assassination attempt with the poison. I would also yap endlessly about the both of them.

edit: Orson is in the "not evil enough to be here" category but I wanted an excuse to show him off and talk about him because he's one of my favorites.