Robert Hare's Psychopathy Checklist:
glib and superficial charm
grandiose sense of self-worth
pathological lying
callousness and lack of empathy
cunning and manipulative
lack of remorse or guilt
shallow affect
need for stimulation
parasitic lifestyle
poor behavioral controls
sexual promiscuity
lack of realistic long-term goals
impulsiveness
irresponsibility
failure to accept responsibility for own actions
many short-term marital relationships
early behavior problems
juvenile delinquency
revocation of conditional release
criminal versatility
I once had a boss who was like this and it took a long time before he was caught doing some really dark stuff to people. Most of the time when you hear hoofbeats you think horses and not zebras, but sometimes it's a zebra.