As mediocre as 
Dracula 2000 (2000) was, it contained one of my fave 
character origin twists in a film. A romanticised villain like Count Dracula being the cursed byproduct of an even more notorious individual from the annals of Western culture was surprisingly unique. This sparked the question: what other treacherous snakes out there are synonymous in film and television? Below, are ten individuals that I felt answered this question. Here are the most odious bunch that instantly come to my mind (or until I realise there's someone out there even worse):

Claude Gaspard: Jacques Becker's Le Trou (1960) accomplished two great feats for this film fan: it simultaneously became one of my fave French films and prison movies. Trust is a vital component in Becker's film and it's even more valuable as the viewer is witness to all that entails in a detailed jail break attempt. It almost feels like it's filmed in real time with the lengthy breaking concrete scene. Gaspard being the new lad in the cramped cell eventually proves his fellow inmates' suspicions correct with his eventual snitching. It's a heart wrenching ending since Gaspard's inmates exhibited such noble camaraderie and put so much time and effort only for it to be snatched away from them by this backstabber.
 Fredo Corleone:
Fredo Corleone: Perhaps one of the most famous moments from 
The Godfather films is Michael Corleone's 
"I know it was you, Fredo." scene , but it was a long time coming for the frail brother after taking sides with 
Moe Greene. The mafioso saga takes a Shakespearean turn when Michael realises his older brother Fredo had unwittedly helped conspire an assassination attempt upon him. Since birth, Fredo was the weakest of the Corleone clan and it's no surprise the 
family's rivals would wind up exploiting him in one form or another. It would eventually lead to his classic off-screen death. Sadly, it was followed by a 
confession in the final film, where Michael comically wolfed down a chocolate bar in the unintentionally hilarious third film.
 More than likely a graduate from The Gordon Gekko School of Ethics & Economics, Carter Burke has got to be amongst the most dastardly corporate scumbags to ever grace the silver screen. His attempt to smuggle a dangerous, alien xenomorph through quarantine by 
Ripley and Newt becoming impreganted hosts earnt him the mantle of secondary villain in 
Aliens (1986). A nice twist of fate is his famous 
deleted scene after Burke locked the door to the medical bay during Hudson's last stand. Goreman may have always been an 
"asshole", but at least he redeemed himself by going back for Vasquez when she was injured.
 John Smith:
John Smith: A shame the television series 
The Man in the High Castle was a mess, as it featured one of the most intriguing villains in it. Based on a novel by Philip K. Dick, this alternate history series, where the Axis Powers seize control over much of the world after their victory in WWII, shows John Smith, a former US army captain, becoming one of the most powerful men in the Third Reich. Smith's commitment to his family in this 
nightmare world ultimately transforms him into the very monster he fought against. From wearing the swastika armband to 
ruling Nazi occupied America, Smith is one of the most monsterous examples of a man who sold out his 
fellow brothers and his country. 
 Kent Brockman:
Kent Brockman: There's no about heel turn as swift as witnessing Kent Brockman's complete selling out of the entire human race when he mistakenly assumes astronaut Homer Simpson's spaceship has been conquered by giant alien ants. This embarassing assumption surprisingly works as a satirical, yet poignant take on today's lack of scruples in modern journalism. It also gets farcically worse as he offers to exploit his celebrity status to help round up humans as slaves for 
"our insect overlords". Both simultaneously comical and disturbing since it has me asking: how many others out there would sellout at the drop of a dime if ever a ridiculous premise like this occurred? Fiver on Piers Morgan!
Ephialtes: Originating from the name of the shepherd who betrayed King Leonidas and his three hundred Spartans to the Persians at the Battle of Thermopylae; his name has 
forever been synonymous in the Greek lexicon with that of history's most infamous traitor. His depitction in 
300 (2007) as this grossly deformed and pathetic individual lends no revisionist sympathy in altering his status as one of the ancient world's biggest sellouts. Witnessing his submission to King Xerxes to for 
wealth, women and a traitor's uniform even pisses off blokes like me - over two thousand years later! Meanwhile, no one ever mentions Theron.. 
"Traitor!"  David Kleinfeld:
David Kleinfeld: Not content with giving us a horrible rat bastard like 
Omar Suarez in 
Scarface (1983), Brian De Palma gave us three more treacherous scorpions in the forms of 
Lalin, 
Pachanga, and worst of all, David Kleinfeld in 
Carlito's Way (1993). This wretched lawyer posing as Carlito's friend not only planned to false testify against a reformed Carlito, but robbed a million from an 
imprisoned mob boss. Drugged out and constantly higher than his own hairline, Kleinfeld was one of the most untrustworthy people out there and woe betide anyone foolishly considering his as a friend. The only positive attribute about him was his taste in women was better than Carlito's, since 
Steffie was well fit and way hotter than Gail.
 George "Buck" Flower had an entire career playing winos and bums. Simply credited as "Drifter" in John Carpenter's alien conspiracy film 
They Live (1988), it's perhaps his most memorable role. Transforming from a 
homeless nobody into a wealthy somebody raises the question of how many others out there, with nothing but their souls, would sell that to gain an advantage in life?  Drifter's speech to Nada and Frank is one of my favourite quotables from the film: 
"What's the threat? We all sell out every day, might as well be on the winning team." and has appeared in other 
media ever since. Holly is another backstabbing trairor featured in 
They Live, too.
 Rifki:
Rifki: Having to do porridge is harrowing enough, but serving it out in a Turkish hellhole like the one from Alan Parker's 
Midnight Express (1978) has to be a fate worse than death for any normal folk. Foreign prisoners have it even worse, as they're treated lesser people by both their fellow inmates and by sadistic guards like 
Hamidou. Rifki, the guards' sneaky and treacherous lapdog makes life even more unbearable for westerners like Billy and Max. The lowest of the low, Rifki even kills 
Max's cat for his own personal pleasure. Fortunately, the snake finally gets his 
comeuppance when Billy flips his shit and silences his tongue. Shame he didn't die, though.
Colonel Nicholson: While other contenders listed here lack any sense of honour whatsoever, Col. Nicholson's is completely fuelled by it. It's a form of 
hubris where it drives him to blinkered madness in aiding and abetting his Japanese captors with 
building a bridge that would be part of their strategic war effort. Nicholson effectively turns into an enemy collaborator and only realises it until his last seconds of 
sanity return to him before his redemptive death. Nicholson's descent into treachery where he rallies his fellow British PoWs in helping with the Japanese is a sight to behold and one that would warrant plentiful discussion by any film heads turned armchair shrinks out there.
 Other Dishonourable Mentions: 
Brockley from Daleks' Invasion Earth 2150 A.D (1966); Guy Woodhouse from Rosemary's Baby (1968); Edmund Yates from Frightmare (1974); Stephen "Flyboy" from Dawn of the Dead (1978); Turkey from The Wanderers (1979); Slater from Only Fools and Horses (1981 - 2003); Miguel from Day of the Dead (1985); Grant from Die Hard 2: Die Harder (1990); Cypher from The Matrix (1999); Salvatore "Big Pussy" Bonpensiero  & Adriana La Cerva from The Sopranos (1999 - 2007); Scud from Blade II (2002); Stringer Bell from The Wire (2002 - 2008) and Koba from Dawn of the Planet of the Apes (2014).