Superman
To dream of Superman represents behavior that rescues or "saves the day" when all else has failed. Power or strength in the face of overwhelming adversity. Enormous sacrifices being made for which you or someone else refuses to give up on. Displaying enormous courage to "hold on" in the face of impossible odds. Super-human courage or willpower. Resisting corruption or negativity to a scale that is unheard of in normal people. Disbelief or shock at how strong you or someone else has behaved.
Negatively, Superman may reflect the belief that you are too strong or powerful to have to listen to a powerful opponent. Believing in yourself too much or believing that you are too strong to face real opposition. A dislike of having to withstand an enormous problem that takes all your willpower and heart to overcome.
Superman in a dream may also reflect a tendency to put to much effort into helping or "saving" people who don't deserve it. Exhausting yourself to protect something vain or superficial.
Example: A man dreamed of seeing Superman struggling to hold up a boulder falling from the sky with all his strength. In waking life he was undergoing the most difficult spiritual test of his life which required no food, water, sex, or social contact for days on end.