Luis is a smooth-talking cad who shows up mysteriously to aid Leon from time to time before running off. He claims to have been a policeman in Madrid before later admitting that he was also once a researcher for Los Illuminados. He does his best to help Leon and Ashley.
The Atoner: He goes well out of his way to help Leon and Ashley because of the responsibility he feels for the situation at hand.
The president's daughter that Leon must rescue in 4.
Armor Is Useless: Averted. You can shoot the trap she was in with a rocket launcher and not kill her with it, also conveniently preventing any game overs due to a misfire. Later, when you unlock an alternate costume that is a literal suit of armor, she is both too heavy to be captured by mooks and invulnerable. Thus, having her stand in the center of a mob while shooting enemies around her works exceptionally well.
The Chick: While most of the time she's pretty much a Distressed Damsel, there's a few times in which she makes herself useful, piggybacking over locked gates to unbar them, helping out whenever there's more than one winch to turn, etc. She also drives a massive truck through a tunnel so Leon can focus on shooting up the Ganados trying to halt their progress.
The Dev Team Thinks of Everything: A minor example. When you play with the default outfit, Ashley won't let you look under her skirt if she's above you (she'll close her legs and admonish you for trying). Play with the second outfit (where she's wearing a pop-starlet kind of outfit with a pair of long pants) and she doesn't respond if you try the same thing.
Distressed Damsel: She sticks with you for a couple of chapters when you first find her before traps in the castle separate you. The next two times you find her, she winds up kidnapped again by the end of the chapter.
Gameplay and Story Segregation: When in her armor, she cannot be carried off by mooks. However, cutscenes will show her first outfit even if she was equipped with the armor. Hilariously, a scene shows her being carried off by a mook while wearing it when you reach Saddler's island.
Stone Wall: Armor Ashley is completely invincible to any form of attack. It is a perfectly viable strategy to use Armor Ashley to lure enemies away from Leon as he snipes them from a distance... with a rocket. Ashley will be perfectly fine.
Sweater Girl: Her sleeveless sweater (even though she is wearing a full sweater around her neck).
Ashley uses the same controls as Leon, but since she never finds any weapons in her chapter, you're not supposed to be able to fight. If you manage to hit a monk with one of the doors, though, you can run up and use one of the context-sensitive melee commands. Sadly, said ability only works in the original GameCube release.
Consummate Professional: Even people she's worked with for years know next to nothing about her personal life. The closest thing we get to hint is an anecdote in a file of her telling off her mother for calling her at work about her personal life, insisting her work is her number one priority.
Friendship Moment: In 6, when Leon asks Hunnigan to fake his and Helena's deaths so they can chase Simmons to China, she barely hesitates. In fact, the reason they know where he's going is because she already put a tail on him. They're accusing a respected superior of a crime they themselves are the prime suspects in, without any evidence to back them up, and she believes them immediately.
"Got a collection of good things on sale, stranger!"
A strange pirate-merchant guy introduced in RE4. Clad in a black, hooded coat and purple neckerchief, the Merchant would be available at some point during the level to sell and buy items. He's a mysterious and quirky fellow and gained quite the fanbase as a result.
British Accents: For whatever reason, he is voiced with a Cornish/rural accent, commonly thought of as a "pirate" accent.
The true mastermind behind the events of Resident Evil 4. He had Krauser capture the president's daughter in order to infect her with Las Plagas and then return her to the White House (after collecting ransom, of course), where she would presumably attack and spread Las Plagas throughout the United States. His plans were foiled by Leon and his crew.
America Saves the Day: Saddler references this trope before fighting Leon and promises to subvert it. This of course is ultimately played straight.
Big Bad: This is the man behind both Mendez and Salazar.
Catch and Return: If you pump enough bullets into him during the Separate Ways boss fight, he fires them back at Ada by forcing them out his finger.
Combat Tentacles: These are most prominent during his boss fight in Separate Ways. He also kills Luis with a tentacle from between his legs, in a move that fans affectionately call the "Wangpale."
Deadpan Snarker: Conversations between Saddler and Leon can best be described as snark-offs.
Faux Affably Evil: All the way. When Leon makes quips at his expense, Saddler always responds with a good-natured chuckle before telling him in a conversational tone how he's going to kill him, and never lets on that Leon is anything more than a source of amusement for him. Even when Leon manages to rescue Ashley at the Island after being cured of Las Plagas via chemo, Saddler's only reaction is to express amusement at him for managing to foil his plans before transforming.
Flash Step: He's quite fond of using this during his boss fight with Ada. Unlike Wesker, he doesn't use it to dodge bullets.
Hive Mind: Using supersonic waves from his staff, he can control anyone or anything who hosts a Plaga, with a few possible exceptions.
The entire plot of Resident Evil 4 makes considerably more sense on every possible level if you assume that receiving his master Plaga turned Saddler into a delusional psychopath who's unwilling to admit that he could possibly be wrong or be defeated.
As part of his research, Saddler had Luis build a machine in the research building that could kill Las Plagas without damaging the host under certain conditions. Knowing full well that the machine was still operational and that it was very near where he was holding Ashley, Saddler made no effort to destroy the machine. Lo and behold, Ashley and Leon found it and used it to get rid of their parasites.
Religion of Evil: Whether or not Saddler actually believes in the religion of Los Illuminados is unclear, but he is their leader and is at least using them as a cover for his own goals.
Softspoken Sadist: He almost never raises his voice and speaks in a polite, soft tone, even when faced with defeat.
Super Speed: In human form, Saddler can move very quickly. He almost seems to hover along the ground as he does so.
Villain Ball: His persistence in keeping Ashley for ransom. Had he just quietly returned her, or allowed Leon to rescue her before he could get to the bottom of things, nobody would've known she was infected untill it was too late.
Villainous Breakdown: Saddler tries to keep a normal appearance throughout the game. Once he discovers that Leon found a way to remove his Plaga, and Ashley probably did too, Saddler goes mad and mutates into a mass of legs and tentacles.
Why Don't Ya Just Shoot Him?: Despite his many, many opportunities to kill Leon, Saddler never gives up hope that Leon will succumb to Las Plagas and, in turn, his mind control. This comes back to bite him in the end.
Voiced By: Rene Mujica
The eighth castellan of the Salazar family castle and a high-ranking member of Los Illuminados, Salazar played a huge part in Saddler's plans by excavating fossilized Las Plagas and donating them to his cause. His goal was to create a world without sin: after all, if people have no free will, how can they do evil? He causes Leon a lot of trouble when Leon and Ashley wander into his castle.
Bratty Half-Pint: An adult version. He's a grown man with a midget body, and his tantrums is that of a little spoiled brat.
Butt Monkey: To Leon. You can tell Leon enjoys trolling the guy.
Trap-Door Fail: He tries to kill Leon by having him fall into a pit of spikes. It fails of course.
Villainous Breakdown: The first major villain of the game, Mendez, ends up nearly killing Leon every time they meet. In contrast, Leon always has a cool head when talking down Salazar, despite Salazar's efforts, and that drives him insane.
Salazar: I've sent my right hand to dispose of you.
Older Than They Look: Salazar somehow manages to look like both a preteen boy and a withered old man, so his age is a surprise if you make an assumption either way.
Voiced by Jim Ward
An antagonist in 4, he literally shows up in the last section of the game, though he's one of the causes of the whole mess: He's the one who originally kidnapped Ashley. Also a playable character Darkside Chronicles, which serves as his Start of Darkness, showing the actual mission he worked with Leon and why he hooked up with Wesker.
Blade Below the Shoulder: In addition to increased speed and endurance, the infection also mutates his left arm into a gigantic metal blade which you can use in the Mercenaries minigame.
Dirty Coward: Played with in Darkside Chronicles. In the last few missions, Krauser essentially breaks under the strain, scrambling with fear from the giant viral monsters attacking him and Leon, even (mentally) desperately begging Leon to save his ass when he thought the odds were too great. Despite all this, and an extremely injured arm, he fights competently and professionally and never really lets any of this show.
The game justifies this as a result of an extensive military career; his professionalism and experience tends to be highlighted throughout the campaign. Which makes The Reveal of his inner thoughts to be all the more frightening. The point at which you realize just how disassociated his thoughts are from his actions is when the warning bells start going off.
Disney Death: Played straight and subverted. You would think beating the tar out of him with Leon and having a stone tower explode and collapse on him would be enough to kill Krauser. It doesn't, but Ada later manages to put him down for good anyways.
Evil Counterpart: For Leon. Both are Knife Nuts, worked for the US government, and even served on the same mission in Darkside Chronicles. Ironically, Krauser falls to the dark side because he liked his work with SOCOM so much, so when he all but loses one arm and faces an end to his military career, he turns to Wesker.
Face-Heel Turn: Ends up turning to Wesker (and presumably faking his own death).
Mistreatment-Induced Betrayal: One of the major factors in his allying himself with Wesker was because of deep anger about feeling used by the United States Military, especially when they didn't even request for him to join up with the organization to stop bioweapon threats, yet they allowed Leon to join, and later their firing him because the Javier mission had him injured in his arm with it not fully recovering. That would probably explain why Krauser, despite swearing an oath to his native country, was perfectly willing to undergo a mission to kidnap the President's daughter.
Good Scars, Evil Scars: The giant scar on his face is supposed to make him look more intimidating. When he puts war paint on his face, it lessens the appearance of it.
Green-Eyed Monster: Has shades of this when he learns about Leon's being ordered to join the secret organization to stop bioweapons, despite the fact that Krauser, at least in his viewpoint, would have willingly joined up to aid the government to get rid of the bioweapons, and yet was not even given that chance.
Remember the New Guy: "I died in the crash 2 years ago... Is that what they told you?" What crash? What mission? Who are you?
Rival Turned Evil: Darkside Chronicles lays out the rather tragic story. Leon and Krauser only knew each other for the one mission, but they earned each other's respect and friendship and from Leon's point of view, parted as friends. In reality, because of a combination of the insane stress of the mission, fear of rejection by the government after major injury, and subsequent fascination for power with which he could liberate himself from others' control, Krauser sought after organic weaponry to augment himself immediately after that mission, breaking all bonds with Leon and the US government (although the fact that the US government fired him because of his injury was probably a huge factor in that last part of his viewpoint).
Shell-Shocked Veteran: Similar to Gray Fox, Jack Krauser feels he is useless outside of the battlefield, and that being a soldier is his calling, to the extent that he often underwent mercenary missions even when he was off-duty from SOCOM. This is a large part of the reason why he ultimately turned to Wesker's help after the US Government fired him due to his arm injury never really recovering.
Also looks a lot like the T-103/Mr. X, leading to some early speculation that he was one.
Genre Savvy: He probably has the least tightest grip on the Idiot Ball in comparison to the other villains and is shown to be fairly competent. Leon has had his ass kicked by him several times and even barely escaped death at his hands.
Half the Man He Used to Be: When half of his health is depleted during his Boss Fight, his upper body rips away from his legs, forcing him to climb on the rafters to attack you.