Can't pick just one... XD
Xenoblade - Final Boss
http://www.youtube.com/watch?v=NT5rjag9klg
Mario Galaxy - Final Bowser
http://www.youtube.com/watch?v=Sfr6Oy0Unzg
Mario Galaxy 2 - Bowser's Galaxy Generator
http://www.youtube.com/watch?v=vk3mSnHdTT8
Metroid Prime - Chozo Ruins
http://www.youtube.com/watch?v=B4QuDXuYG-8
Donkey Kong Country - Fear Factory
http://www.youtube.com/watch?v=v18pEFQb3EM
Donkey Kong Country 2 - Hornet Hole
http://www.youtube.com/watch?v=uiXh9hfLSJw