A brief look at the villains from your favourite books and films will reveal some common personality traits; they're all a few sandwiches short of a picnic. This is of course true of video games too, with many antagonists - who are more often than not found in the form of boss battles incidentally - displaying qualities that would suggest they're not quite with it upstairs. Here then, are the ten most psychotic characters that have appeared in video games.

Dr. Ivo (Eggman) Robotnik - Sonic the Hedgehog series


Sonic's arch nemesis might have a PHD and an IQ of 300, but there's no denying that he has some serious mental problems. Kidnapping bunnies, birds and other cute mammals and turning them into fuel for robotic enemies, an obsession with taking over the world, and a maniacal laugh that could be described as anything but sane. What's crazier than all this is the fact that even with his vast intellect and knowledge of science and robotics, he's still unable to kill a single blue hedgehog. He really must be crazy if he thinks doing the whole thing for a fourth time in Sonic's upcoming return to 2D is going to be any different. Give it a rest already Eggman.

Sander Cohen - Bioshock


The fall of Andrew Ryan's great underwater city Rapture would be enough to send any of its citizens a bit mad, but some took it considerably worse than others. Sander Cohen was once a respectable poet, sculptor and playwright, a man of many talents who also reigned over Rapture's Fort Frolic. When the city descended into chaos, however, Cohen became sadistically impassive to the death and suffering of others. When the player first meets him, he has plastered his disciple Kyle Fitzpatrick to a piano rigged with explosives. It's certainly an interesting introduction, and the explosion that follows is a clear indication of just how kooky the fallen artist has become.

M. Bison - Street Fighter series


The leader of the mysterious Shadloo organisation, M. Bison (known as Vega in Japan) has been a staple ingredient of the Street Fighter series since Street Fighter 2. For proof of the evil dictator's insanity, all you have to do is win a few rounds with him. "Your despair feeds my power!" he sometimes shouts; other times he taunts his defeated foe with the immortal line: "That was delicious!" Even his special moves are based around his mentally unstable tendencies; the powerful Psycho Crusher being one of his signature moves. Bison may be a psycho, but he's a composed and calculated psycho - the worst kind to be up against in a fight.

Psycho Mantis - Metal Gear Solid


"So...you like Castlevania, do you?" Psycho Mantis taunts in one of the most memorable boss battles of all time. How the hell does he know that!? This gasmask wearing loon can't actually read my mind can he!? Well, not quite, but FOXHOUND renegade Psycho Mantis can certainly read something: your memory card, and if there are any Konami save games on there, he'll know. It wasn't just this that gave Mantis an unnerving edge, however; after delving too far into the mind of a serial killer in an interrogation, Mantis adopted his appetite for killing, and became psychotic himself as a result. The gas mask that hides his disfigured face only adds to Mantis' deranged persona.

Origami Killer - Heavy Rain


Who is the Origami Killer? I know, but I'm not going to say because that would spoil the surprise. Just know that anyone who kidnaps kids and then drowns them in rainwater is one messed up individual. More so than any other game, Heavy Rain allows players to see into the minds of each of its protagonists, making the eventual reveal something very special indeed. It's one of the greatest 'who dunits' in video game history.

James Lynch - Kane and Lynch


Paranoid, schizophrenic, and completely out of his mind, James Lynch is one of video games most illustrious nut jobs. Doctors were obviously aware of this too, as Lynch is required to take prescribed medication to keep his raging psychotic outbursts in check. If it wasn't for his slightly more rational sidekick Kane, there's no telling what kind of trouble Lynch would find himself in. Despite his somewhat unstable nature, Lynch is a top guy to have on side in the midst of a violent and bloody struggle with a heavily armed mercenary group. Kane's a lucky guy.

Serial Killer X - Condemned


It's clear that somebody has issues when they decide to start killing other serial killers. Not only this, SKX (as he's affectionately known) kills his victims in the same sick and twisted fashion that they killed their own. With a strange obsession with the main character Ethan Thomas, SKX uses mind games to manipulate the poor detective, which provides Condemned with some of the scariest set-pieces in video game history. SKX isn't just a psycho; he's a criminal mastermind with the kind of power to send a whole town (and in turn the player) into the depths of chaos.

Pigsy - Manhunt


Rockstar's gruesome Manhunt is full to the brim with the mentally unstable. In a twisted gameshow orchestrated by an even more twisted director, the dregs of the criminal underworld are all thrown into a sick survival match with one James Earl Cash as the star. In this frightening gameshow, one enemy was slightly more unnerving than the rest; Pigsy - A chainsaw wielding man-pig that relentlessly chased the player around a decrepit building. More horrific than this was the accompaniment of disturbing snorts that Pigsy made as he ran. This list contains a fair few head-cases, but out of all of them, Pigsy is the one you'd least like to meet in a dark alley...

Kefka - Final Fantasy VI


Chances are you were expecting Sephiroth somewhere on this list, right? While true that Sephiroth wasn't quite the full shilling, the infamous Kefka of Final Fantasy VI is a much better representation of the term 'psycho'. With a dark sense of humour and trademark high-pitched cackle, Kefka earned himself the nickname 'Psycho Clown' amongst fans, a name that was reflected in his jester-like appearance. The first test subject as a Magiteck Knight, Kefka was gifted with powerful magic, but it was too much for him and shattered his sanity. Immensely powerful and stark raving bonkers at the same time; a combination that doesn't bode well for the heroes of FFVI...

Harman Smith - Killer 7


If we were in a more boisterous mood, we would have used each of Harman Smith's seven personalities as an individual entry in our top 10, but for the benefit of time, space and indeed our own sanity, we have limited the character(s) to a single entry. In his head, Harman Smith assumes the role of one of seven personas (collectively known as the Smith Syndicate), all of which have unique traits that enable him to carry out his duties as an assassin with alarming success. Garcian Smith, Dan Smith, KAEDE Smith, Kevin Smith, Coyote Smith, Con Smith and MASK de Smith are seven parts of a unique killing machine. Harman Smith is not a person you want to be on the wrong sides of.