Why is Moonlight sonata always used in horror themes?

does it have any background on why it's being depicted that way in shows?

for example in an episode of the anime Detective Conan, when the serial killer has victimed someone, it will be played so that people will believe it is cursed and thus the murderer will trick them into believing.

another is from a Resident Evil game. I just heard it is played at a certain part of its plot.

I would guess that it might be employed in the instances you cited, not to underline the horror of the depicted scene, but to characterize, contrast the "irony" of it.

Just a thought. I've not seen either movie you mentioned.

Wotan

lol ..and another was shadowman , a game for Sega dreamcast . I have no idea why this is the chosen song for horror or violent flashbacks ...but I like it .

And forget sexual healing ...i'd want this song to be played while i'm having sexual proclivity with the wife/girlfriend.

honestly...it's probably used simply because it is so famous. The piece is so well-known that it would be nearly impossible for a music supervisor to use it in a way that would truly add to a movie scene and have it be unique, poetic, or profound. The problem is people already have their own ideas of the piece before ever putting an image with it. The only benefit to using the piece at all is so the viewer will say "Hey! I know that piece!" and then the person may enjoy the scene a little more because of that. It also is probably used because the music supervisor realizes that the piece will sell. If a soundtrack is made...having the moonlight sonata will up the chances of it being bought.

I can't say that I have ever seen a horror movie that used this piece. It would appear to be entirely inappropriate for a horror movie....very strange choice of music.

Obviously, it's because of the different ways Beethoven uses Neapolitan harmonies throughout the movement. Scary!

the Moonlight Sonata was also used in the film "elephant", which was about school shootings.
Beethoven's 9th was the piece of choice for alex, the central character of "a clockwork orange".
i think soothing or uplifting classical music being juxtaposed with violent characters is an ironic device used to make people think twice about the character and motivations of people that might otherwise be written off as monsters.
or perhaps beethoven is the classical black sabbath.
i think beethoven could have had a dark and violent character.

I would imagine that one of the primary reasons it keeps appearing in video/computer games is because the melody is both popular and in the public domain. Producers can use it for free- as long as they don't pull out a Chicago Symphony Orchestra recording of it, that is.