Hypocrisy
Hypocrisy is the act of pretending to have beliefs, virtues and feelings that one does not truly possess. The word derives from the late Latin hypocrisis and Greek hupokrisis both meaning play-acting or pretence.
A classic example of a hypocritical act is to denounce another for carrying out some action whilst carrying out the same action oneself.
There also is a death metal band by that name.
