It is worth considering the evil that these antagonists did during the show.
Clark had his predecessor assassinated. He ordered the commission of war crimes. He arrested and killed dissidents. He instituted the Nightwatch. He stirred up hatred of aliens while dealing under the table with the Shadows. Eventually, he tried to destroy the planet Earth. He fits into the despot category pretty nicely.
Mr. Morden was an agent for a force of chaos and war. He had no scruples about committing murder or genocide. He enabled the Centauri to bombard the Narn with mass drivers. He manipulated people and provided temptation. He fits into the "tempter" category, similar to a lot of stories about the devil.
Lord Refa was simply ambitious, and he would do anything, even destroy the Republic, to reach that ambition. His motives were simple, and ultimately, he was as much a tool as a manipulator.
Cartagia was Caligula. He was insane, and the only reason he stayed in power as long as he did was because he had powerful supporters who took advantage of his insanity.
Sebastian was utterly self-righteous. He was the agent of order, and he expected his charge to meet his standards or perish. It was also basically stated that he was a serial killer.
Bester was a hero to many of his people...and a monster to anybody else. Non-telepath life meant little to him. He expected nothing but scorn and hatred, and he never did anything to merit anything else. His conversation at one point with Dr. Franklin was very telling. Even for his own people, he could be considered a fascist. He fits the role of zealot.
The Drakh were never properly explored...but they played the role of children who have been spoiled and then abandoned. As servants of the Shadows, they were just tools. When the Shadows left the galaxy, their only purpose was revenge.
The Soul Hunters were also convinced they were doing right...and they were perfectly willing to "help" people who didn't want to be helped. They are an example of the antagonist who does what they do "for your own good."
William Edgars was a patriot who saw telepaths as a threat. He was willing to violate the standards of moral and ethical behavior to combat that threat. As an antagonist, he exemplifies the plutocrat who sees the ends justifying the means, confident in their own ability to do what they wish.
The Nightwatch and MiniPax represent betrayal. They are your coworker, family member, or business competitor who can report you for "disloyal" behavior. Because they are so prevalent, they are an insidious influence on everything in society, sowing suspicion.
So, we have the despot, the agent of chaos, the ambitious man, the mad emperor, the agent of order, the zealot, the spoiled children, the sanctimonious false saviors, the plutocrat, and the betrayers. They are all memorable characters strongly influenced by archetypes, and they play story roles suitable to those archetypes.
Overall, Alfred Bester was the most complex character of the group. He showed signs of compassion, and he could work with his enemies when it suited his needs. He was also charismatic, competant, and dedicated. That made the fact that he was a monster even more horrifying.
One last point. Of all the characters in the series, Londo Mollari and G'Kar were the most nuanced, in-depth, and well-portrayed. They had complexities beyond the other characters, and they went through transformations far more interesting than the other characters. Even as Lennier was led to betrayal through love, Sheridan became a mesiah figure, and Garibaldi had his loyalties perverted, it was always the two ambassadors that were the most interesting to me.
