Welcome to a brand new io9 music smackdown! We're putting together the ultimate science fiction (and fantasy) playlist — all the music that every self-respecting fan should have on his or her iPod.

Today, help us decide which original music scores absolutely must be in the mix. Which would you rather have in your ultimate science fiction playlist: a little bit of Moon, or some Tron: Legacy?

Here are the rules for this particular playlist. You can vote for four total. The winners will be added to io9's ultimate playlist. The poll is at the bottom of the posts, and we've included every single song on the list so you can decide first-hand. This is a tough section, does one amazing theme song blot out an entire score from another film? Debate amongst yourselves...

Also if we forgot anything, please let us know in the comments. If enough folks agree, we'll add it on! And finally, we lumped large saga films such as Star Wars, Indiana Jones and Harry Potter together for spacial reasons. When you vote for Indiana Jones, that's a vote for the whole collection.

Remember: you can vote for up to four items.

Poltergeist - Jerry Goldsmith

Metropolis - Gottfried Huppertz

Pan's Labyrinth - Javier Navarrete

The Dark Knight - Hans Zimmer and James Newton Howard

Star Wars - John Williams

Coraline - Bruno Coulais

Superman - John Williams

Dune - Toto & Others

The Thing - Ennio Morricone

Jurassic Park - John Williams

The Day The Earth Stood Still - Bernard Herrmann

Let the Right One In - Johan Söderqvist

Harry Potter (1,2 & 3) - John Williams

Moon - Clint Mansell

Sunshine - Underworld & John Murphy

Attack The Block - Basement Jaxx

Hanna - The Chemical Brothers

The Matrix - Don Davis

A.I. - John Williams

Tron: Legacy - Daft Punk

E.T. - John Williams

Lord of the Rings - Howard Shore

Hook -John Williams

The Omen - Jerry Goldsmith

Halloween - John Carpenter

Dragonheart -Randy Edelman

Nightmare on Elm Street - Charles Bernstein

Friday the 13th - Harry Manfredini

Indiana Jones - John Williams

King Kong - Max Steiner

Star Trek: The Motion Picture - Jerry Goldsmith

Star Trek II and III - James Horner

Close Encounters of the Third Kind - John Williams

Dawn Of the Dead - Goblin

The Bride of Frankenstein - Franz Waxman

Edward Scissorhands - Danny Elfman

Krull - Jamer Horner

Gremlins - Jerry Goldsmith

Planet of the Apes - Jerry Goldsmith

Beetlejuice - Danny Elfman

Blade Runner - Vangelis

Pirates of the Caribbean: The Curse of the Black Pearl - Klaus Badelt

Stargate - David Arnold

Young Frankenstein - John Morris

Terminator 2: Judgement Day - Brad Fiedel

Bram Stoker's Dracula - Wojciech Kilar

Forbidden Planet - Bebe & Louis Barron

Gattaca - Michael Nyman

Back to the Future - Alan Silvestri

Princess Mononoke - Joe Hisaishi

Alien - Jerry Goldsmith

Inception - Hans Zimmer

Men In Black - Danny Elfman

The Incredibles - Michael Giacchino

The Witches of Eastwick - John Williams

Conan The Barbarian - Basil Poledouris

Batman - Danny Elfman

How to Train Your Dragon – John Powell

Up – Michael Giacchino

The Amityville Horror – Lalo Schifrin

[assocaite]

Interview with the Vampire – Elliot Goldenthal

Eternal Sunshine of the Spotless Mind - Jon Brion

Not technically an original work (or, not an original work at all) but we felt they deserved a mention in this category, and should compete in this heat:

A Clockwork Orange - Wendy Carlos & Classic Musicians

The Exorcist - Mike Oldfield's "Tubular Bells"

2001: A Space Odyssey - Various classical works

Previously:
Vote for the greatest use of pop music in all of science fiction and fantasy
Vote for the greatest animated TV theme song of all time
Vote for the greatest science fiction theme song of all time