http://en.wikipedia.org/wiki/Pathological_liar In psychology, mythomania (also known as pseudologia fantastica or pathological lying) is a condition involving compulsive lying by a person with no obvious motivation. The affected person might believe their lies to be truth, and may have to create elaborate myths to reconcile them with other facts. Among famous mythomaniacs in history was King Frederik VII of Denmark and Sir Douglas Conway of Suffolk. A pathological liar is someone who often embellishes his or her stories in a way that he or she believes will impress people. It may be that a pathological liar is different from a normal liar in that a pathological liar believes the lie he or she is telling to be true—at least in public—and is "playing" the role. He or she sometimes is seen to have a serious mental problem that needs to be rectified.