"You start believing in that 'peace on earth and goodwill stuff,' there's no telling how screwed up you'll be."
Heartbroken Badass: When he was a U.S. soldier in Vietnam he married a Vietnamese woman and had a daughter with her, but both were killed when the place where the U.S. army said they would be safe was napalmed by a U.S. plane.
Heroic BSOD: After being forced to (nearly) assassinate Donovan, he so completely shuts down that Farber practically has to carry him. He gets better, of course.
Malaproper: Was supposed to have been placed in the Middle East and so had learned Arabic, but paperwork got shuffled around and he ended assigned to the U.S. and had a very short time to learn English, leading to this trope.
Nice Guy: Very nice, extremely kind, and almost invariably sweet.
Punch Clock Villain: Was a simple low-level grunt among the Visitors, doing as he was told (and actually genuinely friendly towards humans), until he was captured by The Resistance.
Dragon-in-Chief: She was the real orchestrator of the Visitor invasion despite only being the second or third person in the chain of command of the Visitor Fleet orbiting Earth. She eventually points this out to Supreme Commander John, and he spitefully notes that she can reign all she wants over a destroyed Earth.
Klingon Promotion: She murders several of her superiors in cold blood to usurp their position, arguing that she favors a "more direct approach" to behind-the-scenes schemes among the officer staff.
Mad Scientist: She regularly performs "experiments" on captured prisoners. Donovan sees the gruesome results to one of his friends of one such experiment. She's also stated to be the one who invented the method for preserving humans as food for the Visitors and came up with the plan to harvest humanity.
Mind Rape: She perfected the process with the conversion procedure. The subject is tortured with vivid, nightmarish hallucinations until they either become completely docile or are turned into a drooling vegetable.
The Mistress: She was a mistress to the Visitors' Leader to advance her own career. Pamela notes how little he must care for her to send her on a mission several hundred lightyears away.
Torture Technician: She perfected a brainwashing procedure that plays on the subject's primal fears and which she often carries out herself, both for her expertise and fun.
The Vamp: She usually doesn't fool anyone, given that most people are aware that she's a reptilian alien underneath her human suit. However, in the weekly series she seduces a random driver to kill him and steal his car while she's on the run.
Villain Exit Stage Left: Subverted. She exits the second miniseries by taking an escape pod, but in the weekly series Donovan quickly catches on and chases her down to stand trial for war crimes.
Big Bad Wannabe: He figured that he was the Supreme Commander who would win the campaign on Earth for their Leader. Diana eventually reminds him that he was just a useless figurehead.
Even Evil Has Standards: He's disgusted with Diana when she tries to annihilate all life on Earth with a nuclear bomb during the Visitors' retreat.
Evil Old Folks: His real age is unknown, but his human guise is old enough to have completely white hair. He's also the regional leader of a fascistic alien invasion force.
Manipulative Bastard: He presents himself as a benevolent alien who has come to mankind for help. His real plan is to install a puppet regime on Earth so he and his men can slowly drain Earth of its resources — food and water. And the "food" happens to be those humans who aren't drafted as shock troops in their other campaigns.
Alpha Bitch: Not as much as Diana, but she can be just a cruel and selfish.
"I know the Visitors aren't saints. But they're in power! They are power..."
Papa Wolf: Even though he and his son pretty much disagree on everything, and he's more than willing to set Mr. Chiang on his son to teach him a 'lesson', he'll do anything to protect Kyle from any trouble he gets into with the Visitors.