We've all had that co-worker at some point: superficially charming, supremely self-confident but they'll walk over anyone to get ahead and not feel a second's remorse.
Perhaps, after you were burnt yet again, you half-joked that they must have a personality disorder.
Today, experts believe it's very possible that your colleague is a psychopath.
Groundbreaking research presented at the Australian Psychology Society Congress in Melbourne this week reveals that one in five corporate workers may have the disorder - as many as in the prison population.
Forensic psychologist Nathan Brooks found that psychopathic traits are common in the upper echelons of the corporate world, with a prevalence of between three and 21 per cent (the latter in a study of supply chain professionals).
The term "successful psychopath" describes high-flyers with psychopathic traits such as insincerity, a lack of empathy or remorse, egocentric, charming and superficial.
Brooks says it has emerged in the wake of the Global Financial Crisis, prompting new research and insight.
Psychopaths are over-represented in the criminal justice system, and we traditionally associate the term with twisted serial killers.
But the typical traits are also highly suited to getting ahead in the business world.
"Usually psychopaths seem pretty normal," Scott Lilienfeld from Atlanta's Emory University, who is also presenting on the topic at the APS Congress, told news.com.au.
"Most are not violent but they are high risk, often getting in trouble and breaking the law.
"They are over-represented in certain occupations: politics, business, high-risk sport. The research on that is in the preliminary stages.
"Being a psychopath might predispose someone to short-term success. They tend to be charming and flamboyant, which makes it easier to be successful in the short-run, although that may be purchased at expense of long-term failure."
SPOT THE PSYCHO
These devious individuals are hard to identify by their very definition. Just as with tallness and shortness, people tend to lie somewhere on a spectrum between psychopath and non-psychopath, according to Prof Lilienfeld.
You should look out for a combination of traits:
• Interpersonal - Superficially charming and self-confident on first impression.
• Affective - Lack of guilt or empathy, don't form deep attachments
• Behavioural - Poor impulse control, lying, cheating.
It's very possible you will warm to the psychopath more than your other colleagues at first. This personality type tends to seem fun and be initially well liked.
That explains why they often obtain rapid promotion, hopping from job to job and climbing the ranks at speed.
Wait a year, Prof Lilienfeld advises, and their true colours are likely to reveal themselves.
"Callous, unemotional traits may be harbingers of psychopathy," he says.
Psychopaths run a high risk of having interpersonal problems, so watch for people who put down their subordinates, cheat in romantic relationships, lie to friends and bounce cheques.
"It's a double-edged sword," he adds. "Being socially fearless could lead to success or trouble.
"Boldness - physical and social - we see as part of parcel of psychopathy.
"High-risk sexual behaviour, anti-social behaviour such as duping and success in the business world.
"It can cut both ways."
While we can't run around diagnosing prominent figures without clinical testing, experts have identified some classic psychopaths from history.
They include Benito Mussolini, Joseph Stalin, Saddam Hussein, and fictional characters such as Shakespeare's Richard III and Cassius.
In a study by Oxford University psychologist Kevin Dutton, published in Scientific American Mind, Donald Trump scored 171, edging out Hitler on 169 but behind Henry VIII (178) and Saddam Hussein (189).
Hillary Clinton slotted in between Napoleon and Nero, on 152.
But Prof Lilienfeld said that while Hitler may have some traits, he doesn't quite fit the mould, because he was "paranoid and odd," while most psychopaths are delightful on the surface.
The dictator's strange ideas and convictions, and relative lack of narcissistic or grandiose qualities, make him more likely to have had a delusional disorder.
Psychopathy can also overlap with narcissistic personality disorder, the professor explains.
Politicians are frequently labelled psychopaths. In July, former NSW premier Kristina Keneally called former Australian Prime Minister Kevin Rudd a "psychopathic narcissist", suggesting her dog would make a better candidate for the UN secretary-general.
HOW TO HANDLE THAT CO-WORKER
No cure for psychopathy has been discovered, and it's uncertain whether one could exist.
"I'm doubtful we'll find a cure, it's more likely to be ways to diminish the risk of getting in trouble," says Prof Lilienfeld.
"We can find ways of treating them, keeping them out of trouble. We might be able to give them skills to control their anger or channel their excitement, go parachute jumping instead of robbing a bank."
Brooks is more sceptical, warning that the successful psychopath could engage in unethical and illegal business practices and have a toxic impact on other employees.
"Typically, psychopaths create a lot of chaos and generally tend to play people off against each other," he says.
He and his research colleagues, Katarina Fritzon of Bond University and Simon Croom from the University of San Diego, have developed a corporate personality inventory tool to allow businesses to screen for psychopaths during the recruitment process.
"We hope to implement our screening tool in businesses so that there's an adequate assessment to hopefully identify this problem, to stop people sneaking through into positions in the business that can become very costly," adds Brooks.
But if they are so successful, some businesses might still try to gain from the presence of a psychopath, despite the risks.
"They are spectacularly successful in some domains and a spectacular failure in others," says Prof Lilienfeld. "We ask whether they are good or bad, but that is a simplistic way to think about the world.
"They can be adaptive or maladaptive. Most are fairly affable, a few I consider kind of creepy. What I find interesting is why and how they fool us."
We probably all have some psychopathic traits, he notes. It's what we do with them that counts.