Aha, one of my favourite perennial topics (albeit from another forum)!
. I'll throw in what I can off the top of my head and can help out with gear for only a few of them.
Depending on how far back you want to go, there are some classic films which are well known to be the first to feature electronic scores. The earliest of them would probably be Luis and Bebe Barron's extraordinary sounds for
Forbidden Planet.
There's also Bernard Hermann's score for
The Day The Earth Stood Still (lots of Theremin in there)
Fiedel's
Terminator has already been mentioned. AFAIK, synths for that included:
Oberheim system (OB-Xa, DMX and DSX)
Emulator I
Prophet 10 (used for the metallic heartbeat sound)
Grand piano
Electric violin
(also features a cast iron frying pan hit with a hammer! :grin
Terminator II saw the debut of the Fairlight CMI III.
Also nice to see
Blade Runner getting a mention.
Vangelis's go to instrument is always the magnificent Yamaha CS-80 which features prominently here and his other soundtracks, eg:
Chariots of Fire
The Bounty
Conquest of Paradise
Antarctica
etc
Next port of call for me for synth heavy scores would be John Carpenter's films, and a lot of those scores, he did himself along with Alan Howarth.
Carpenter's first film was
Dark Star, the soundtrack of which he did with the venerable EMS VCS3 at a friends house. Then there's:
Halloween
Assault on Precinct 13
The Fog
(all feature the Moog Modular IIIP in varying degrees)
Halloween II
Escape New York
(saw the addition of the ARP Quadra)
Big Trouble in Little China
(1st use of the Prophet VS)
The Thing
(scoring primarily by Ennio Morricone but with a fair bit from Carpenter and Howarth)
They Live
Halloween IV
(Synclavier Digital Audio System, Emulator II, Yamaha DX7, SCI Prophet 10, Prophet 2002 and Prophet VS, Ensoniq EPS, SQ-80, Oberheim 4-voice (rack))
Not to be forgotten is Wendy Carlos's contributions to outstanding synth driven scores. Two of her most popular of which were also Kubrick films:
A Clockwork Orange
The Shining
probably worth mentioning Tron as well
Dario Argento's visceral horror flicks made excellent use of some synth-heavy artists:
Inferno (Keith Emerson)
Deep Red
Suspiria
Tenebrae (all by Goblin, great Italian Prog rockers)
Tangerine Dream did a few:
The Sorcerer
Firestarter
Thief
(are all I can recall for now)
Jack Nitzsche's score for Starman was mostly Syncaliver I think, as was David Shire's score for 2010: Odyssey Two (there's also some Yamaha DX7 and Jupiter 8 in that one as well I believe).
Tony Banks from Genesis (the man who missed out on 2010 and should not have since Shire's score was as disappointing as the film for me) did some UK films featuring piano and synths : The Wicked Lady and The Shout
Speaking of piano and synth, John Harrison did a great score for the first Creepshow movie using only a piano and a Prophet 5 synth.
Rick Wakeman did the Creepshow 2 score but before that, it was The Burning (liberal use of Prophet 5 and MiniMoogs there).
Mike Oldfield's excellent score for The Killing Fields makes extensive use of the Fairlight CMI and Oberheim synths (having just put the Fairlight to equally fantastic use on his Discovery album).
That's as much as I can remember for the moment. Hope that's of some use.
We could also go to TV serials and TV movies but there's almost too much there. My personal favourites are of course Dr. Who, still one of the most original (and one of the earliest ever) electronic signature tunes. Staying with the Doctor, there's Tristram Cary's all electronic scores for the The Daleks and The Mutants (the last one he did for the Beeb before moving to Australia). Malcolm Clarke's Synthi 100 work for The Sea Devils was also quite an ear-opener.
Cheers,
Matt