What trips up a leader?

I've coached, worked with, worked for a lot of leaders.  Rarely is the lack of skills the thing that trips them up. Rather it is a character flaw.  That is, when a leader is keenly aware of his or her strengths and weaknesses, he or she will compensate for them in some positive way.  And they are viewed as a good leader because of it - rightfully so.  A character flaw - lack of humility, arrogance, selfishness, etc - however is the kiss of death.