I can't say there are any truly impossible Bosses, and I haven't played enough games to find any that cause me a major problem. I am more likely to give up on a game because an area is particularly long and contains puzzles which get nowhere (I haven't actually completed Final Fantasy X because of a maze which I found irritating). Anyways, my list of a few problematic Bosses which I eventually beat: Mr X [streets of Rage 1 Syndicate Boss on Hardest] where one 'whack' of his machinegun butt (irritatingly hard to dodge whilst being mugged by white haired punks) left only a couple millimeters of your life intact (seriously) Shao Kahn [Mortal Kombat Trilogy Boss] Charged at you repeatedly, bombarding you with a barrage of attacks - Had to jump over until he used fireball, then jump over fireball and use a combo attack up close (Liu Kang kick combo worked best) Gross [second from last Boss in Last Battle AKA Hokuto No Ken 2] My life would be drained from previous fights and would often not withstand his onslaught. Was 'random' enough for me to never have figured a pattern out. Could fly at you while delivering about 10 rapid punches draining your life. Everytime I beat him, I had only the smallest increment of life left. One game I did not complete because of an unfair continue system and murderous bosses: Bosses of stages 5 and 6 [from Sol-Feace/Sol-Deace (R-type-like space shooter)] Boss 5 would have you dodging between small gaps to avoid bullets from multiple moving 'bullet dispensers' and one huge laser attached to the same frame, and you were forced to stay at the bottom left of the screen while having to initially destry a ship making mini bots which float around waiting to collide with you. Normally if you died on a level you would continue at the start of that level, but if you got to level 6 or 7 and died, youd be taken to Level 5 again! Boss 6 was a nightmare, firing a ring of bullets physically impossible to dodge, homing 'lines' which would trap you in such acute angles that you couldnt escape, and 2 *dreaded* yellow beams which would follow you around the screen and were so long, you barely had room to stop colliding into them. [Yet the funny thing was, after the aforementioned murderous onslaught, you would have to get to the last level, face 2 bosses in a row which were also darn tough (I found this by using level select to check out the later Bosses), only to be faced with your last enemies - A wall where pieces fly off (possibly attempting to damage you) which was easy to dodge, then when the wall gave away - the final Boss appeared... ...and all you had to do was stay near the back of the screen, and do nothing, it couldnt get you! Make a cup of coffee, by the time youve drank it, the boss automatically wouldve blown up itself because you were taking so long - thus the easiest enemy in the game!] There you go, and the moral of the story is: Never make games where Bosses get easier in later levels, it just sucks! And they should have more chicks for Bosses - The closest I know of is when Trish is trying to zap you to death in DMC, but even then she wasnt a central Boss (she just backed up Nightmare), AND she joined Dante in the end!