6. Silent Hill 2 - Pyramid Head And The Mannequins
http://www.youtube.com/watch?v=aHxd0TCSzdE This hugely unsettling sequence has become legendary among horror fanatics as one of the most disturbing scenes in any video game. Opening with what looks like Pyramid Head sexually abusing a couple of mannequins, it culminates with a terrifyingly close encounter in a cupboard.
5. Half-Life 2: Episode 2 - Ending
http://www.youtube.com/watch?v=V2va_Z9AS2k While not technically a cutscene, thanks to Freeman still retaining some control, the ending of Half-Life 2: Episode 2 is one of the most tragic of any video game. It's easy to see why Half-Life 3 is so widely anticipated after this bombshell of a cliff-hanger.