All the others plus:
Walter/Wendy Carlos
Vangelis (get the BladeRunner Soundtrack!)
Jan Hammer - "The First Seven Days" (incredible!)
Jean Michel Jarre
Isao Tomita
T.O.N.T.O. (The Original New Timbral Orchestra)
Mike Oldfield
Depeche Mode - (the early stuff)
Torch Song ("Mothdoom Ecstasy" is my favorite!) vinyl only (unless you are lucky and have the Japan "Wish Thing" CD or certain compilations)
Gary Numan ("Down in the Park" is my favorite)
Thomas Dolby
Yaz (Yazoo)
Fad Gadget
Lauri Anderson
Cabaret Voltaire
NIN (Nine Inch Nails)
The Art of Noise
Propellerheads - "Decksanddrumsandrocknroll"
Brian Eno
Weather Report
Mahavishnu Orchestra
King Crimson
Passport
Pink Floyd
ELP (Emerson, Lake and Palmer)
etc, etc, etc...
Not all of the above artists are totally electronic but contain a good deal of the "electronic sound".
Check out Electronic Music at Wikipedia for more information and links.
For free downloads, check out Open Source Audio and do a search under "electronic". You may find something you like!