"Vampire Killer" from Castlevania on the Nintendo Entertainment System (1986).
Record Label: Konami
Game Developer: Konami
If any song is going to put me in the mood to kill vampires and other associated forms of undead or supernatural abominations, this song does it for me every time. Sure there are a lot of other songs from the Castlevania series that I could have chosen today, but I had to go with what I feel is a quintessential song from such a long running series.
Satoe Terashima has done a phenomenal job with three tones creating a song 28 years old that still resonates with modern audiences. I do not know if I would put this song up with with the "BackGround Music" from Super Mario Bros. or the "Overworld" theme from The Legend of Zelda, but for me it is equally recognizable and just as important.
I know that in later Castlevania games, especially on the DS, the "Vampire Killer" theme is used sparingly, typically near the end of the game and I am perfectly fine with that. I take it as a reminder of where the game originated and is congratulating/thanking the player for playing through the new installment. I have yet to finish any of the newer reboot games so I cannot comment if "Vampire Killer" is used by Óscar Araujo (the composer for the reboot series), but I would not be surprised to hear its motif used later in the game.