Ramon Rojo from A Fistful of Dollars. He is extremely obsessed with a woman, is widely paranoid, and tortures and kills in cold blood. He is a dangerous psychopath and makes a Slasher Smile during many of their massacres.
Golic in Alien³. Even though he didn't kill the two inmates that the others suspect him of having murdered, he is still a homicidal nutcase. When he's contained in the infirmary in a straight jacket, he turns to Ripley and suddenly reminisces about a few women he knew back home. Then he looks her in the eye and says that she's gonna die too.
Morrell in A Room for Romeo Brass appears to be just a lonely eccentric, but he soon reveals his true colours when he threatens a disabled boy with a knife for a harmless practical joke that made him appear foolish in front of the woman he is obsessively fixated upon, threatens to kill the boy's family, and then threatens to kill the boy's best friend (and brother of the object of his lust) when the woman rejects him. However, compared to several of the others on this list he's an unusually laughable and ultimately rather pathetic example; his attempt to make good on his threats is put in its place when the best friend's estranged father — who hasn't taken any of Morrell's shit throughout the movie — charges in, gives Morrell a good kicking and sends him skulking away with his tail between his legs and the promise that, if the boy's father ever sets eyes on him again, he'll be the one who ends up dead.
Loki, the main villain of The Avengers, announces his arrival on Earth by killing a bunch of S.H.I.E.L.D. agents with the evil spear of doom that the Chitauri gave him. He then proceeds to kill many more people over the course of the movie.
Also, Hulk himself can qualify it, in spite of being heroic.
Barnaby: Item 1: Kidnap Tom. Roderigo: * Makes throat-slitting gesture* Gorganzolo: No, just kidnap him. Barnaby: Item 2: Throw him in the sea. Roderigo: * Repeats gesture* Gorganzolo: No, just throw him in the sea! Barnaby: Item 3: Steal the sheep. Roderigo: * Stabbing motions* Barnaby: No, just steal them!
Fouchet, in Bad Boys. His plan seemed to involve killing everyone he encountered. His first reaction when the cops arrive at the end? Shoot his partner.
Kazuo Kiriyama from Battle Royale: He shoots down several unarmed girls, grabs their megaphone and puts it to one girl's mouth so everyone within hearing distance can hear the sounds she makes as she dies.
Wooley from Dawn of the Dead. The guy just runs around the apartment building in the beginning of the movie shooting everybody in sight, whether they were zombified or not. He was so out of control, the SWAT had no choice but to kill him.
Sarah turns into this over the course ofThe Descent. Differs from many examples in that it wasn't a random attack so much as the Ax Crazy making her act on her motivations. Alternately, the movie purposely left open the possibility that she had imagined the creatures and it was really just her slaughtering all her friends. Which would make her much more Ax Crazy, and throughout the whole movie.
Only in the Revised Ending. In the original ending, there's an additional scene which shows her about to be killed by the very-much-not-imaginary creatures while hallucinating that she's back with her dead daughter.
Debbie of Devil In The Flesh. She is an Ax Crazy Yandere who kills numerous people and tries to kill her teacher's wife (she has an intense crush on her teacher).
The Scorpio Killer from Dirty Harry is from this trope in spades.
Chester of D.O.A. enjoys hurting people. He especially relishes the gutshot, since it kills people nice...and slow.
So is a particular scene from Donnie Darko — though the character is Ax Crazy throughout.
Kruger in Elysium. It's crazy enough that he uses his goddamn katana to cook food with. What makes him one of the most batshit insane villains yet is his horrifying reputation for being a human-rights violator and for having very bad habit of blowing people up, going as far as calling an injury that he inflicts on those who get in the way "a flesh wound", before blowing them to chunks. And once he finds out Delacourt's "classified info" was a total system reboot for Elysium, he decides to kill Delacourt and get the data himself to turn Elysium into his personal hell.
Geaer Grimsrud from Fargo. In fact, in one scene he actually uses an ax.
Tommy Devito in Goodfellas. Made even scarier is the fact that he is based off of a real-life gangster.
Jimmy Conway, as well.
Ditto Nicky Santoro in Casino. Also based on a real life gangster, and played by the same actor.
Frank Marino, The Dragon for Santoro, is probably one.
Michael Myers from Halloween is really a subversion. He is more calm and quiet that crazy, but still has several features of a true Ax-Crazy, he's a cold-blooded homicidal maniac without conscience who enjoys killing.
John Ryder in The Hitcher is one of the most chilling and disturbing examples.
Hugo Stiglitz from Inglourious Basterds. He may be one of the good guys, but that doesn't make him any less unnerving: he murdered thirteen Gestapo officers, and when he smiles, it's really truly creepy.
Wicke from Jack the Giant Slayer comes off as just slightly unhinged during a lot of his screen time. Whenever Roderick gives him the cue to either kill someone or that he's going to do it himself, he reacts with glee and excitement, and even when that's not happening, he's usually trembling and/or smiling eagerly about doing whatever it is they're planning to do next.
In Quantum of Solace, Dominic Green becomes this towards the end when James ruins his plans and destroys his entire facility, at which point, he completely snaps and uses an actual axe to try and chop Bond into pieces, all while screaming like a complete lunatic.
Ripper, a fairly generic ax-murderer, is one of the antagonists in Last Action Hero. The fact that he's a hulking, semicoherent clone of every other Ax Crazy slasher on film is surely deliberate, as he's a fictional character from a rather trite series of lowbrow action flicks.
Matilda adds a good dose of Ax Crazy to The Trunchbull in addition to her cruel treatment of her students. The first thing she does when she suspects intruders in her house? She bull-charges from room to room, leaps down from the second floor, bringing down her chandelier in the process, and eventually starts swinging an Olympic hammer around and randomly smashing it into her possessions.
Esther (or better said, Leena Klammer) from Orphan.
Detective Norman Stansfield from The Professional has the habit of murdering families while humming Beethoven, in fits of drug-induced lunacy (though it doesn't help that he is also a death obsessed psychopath).
Arthur Burns from The Proposition is a well read and very deep Warrior Poet...who just happens to have a penchant for gang-rape and mass murder.
Generally implies in Rambo himself as well, specially when he is fighting in battle.
Rippner in Red Eye following Lisa stabbing a pen through his neck.
Repo! The Genetic Opera has Luigi Largo. He's been described as walking around with a flask and a knife, drinking and stabbing anything that gets in his way, including his own employees. He's also tried to strangle his brother in 'Mark It Up'.
I'm the smartest and the toughest! I will find a hole and fuck it! If there ain't one, I will make one! Luigi don't take shit from no one!
The Rocky Horror Picture Show - Never steal Dr. Frank N Furter's spotlight while he's holding a pickaxe. It may be the last thing you do. Meat loaf, anyone? He can also be pretty intimidating with an electric carving knife.
Pooh-Bear in The Salton Sea is both crazy and extremely dangerous.
Tony Montana himself from Scarface. While growing addiction to drugs increases, is getting increasingly aggressive and downright nasty.
Also, Hector the Toad. In fact, forcing Tony to see his friend Angel being dismembered with a chainsaw.
Angela Baker: I've never chopped wood before, but I've chopped other things!
Queen Ravenna in Snow White & the Huntsman. Other versions have always been self-centered, vain, and downright cruel, but this version will kill anyone who defies her without a second thought. Plus the implication that she's killed plenty of kings in the past.
Captain Nero from Star Trek. He wakes up in the morning looking for new shit to blow up. And with advanced tech from the future, he can actually accomplish this. Sometimes he switches it up a little and becomes a Bladed Romulan Sceptre Crazy, instead.
The eponymous killer from The Stepfather films whose sanity is shaky at the best of times, going from perfect All-American dad to a ranting attacker who beats people to death with a wooden board or stabs them in them in the face with a rake at the drop of a hat.
Trigger Happy Lola from The Transporter 2 "Actually, my problem's not medical. It's psychological." (shoots the nurse.) And a few moments later: "What seems to be the problem?" "Me." (yet another burst of gunfire.)
The Yakuza with the Green Shirt (Kenji Mastuda) from Kitamura's Versus is a clear example of Ax Crazy. In fact, he seems to be utterly and completely unable to be serious or show any signs of normalcy through the movie; he constantly makes faces and sounds, laughs like a maniac, screams and overall draws attention to himself by simply being a nutjob in every scene where he's present.
The killer in 7eventy 5ive is both crazy and uses an axe to kill people.
Benoit from Man Bites Dog is a completely unpredictable Serial Killer. His crimes are sometimes motivated by money, but they are generally completely random. At his birthday party for example he's ecstatic about trying his presents... and shoots one of the attendees in the head without warning. He then continues enjoying the party like if nothing happened.