EMI are currently doing a promotion called "Electrospective" and Mojo Magazine this moth have the fifty (in their opinion) , most important electronic albums. This post is in no way definitive and may contain errors and disagreement , but it's really some observation on a lot of the way I saw much of it happening.
The starting point seems to be the soundtrack for the film "Forbidden Planet" by Louis and Bebe Barron around 1956 . Now there is no doubting the importance of this album , totally electronic resulting in eerie incredible sound textures for the film based on William Shakespeare's Tempest.
However none of this would have happened without Les Paul's electrification of the guitar and invention of the multi track tape recorder.
Joe Meek was my first pop introduction to "non normal" sounds , on records such as "Telstar" by The Tornadoes with int's organ treatment .
Around the same time Dr Who hit the screens and Delia Derbyshire and the BBC Radiophonic Workshop brought us Ron Grainer's incredible Dr Who theme , still amazing fifty years on. Delia was part of White Noise who provided us with the wonderful Electric Storm album.
With psychedelia we heard phasing being introduced on records such as Nirvana's Rainbow Chaser and by the time I was taking an interest in music bands such as Hawkwind and Tangerine Dream were the leading electronic lights. My first introduction to Kraftwerk was the flute driven "Ruczuk" , which admittedly had a regimented rhythm and phasing , though with teh release of "Autobahn" they were truly an electronic band.
The Theramin came to the fore notably on Led Zeppelin's "Whole Lotta Love" and the Beach Boys "Good Vibrations" , apparently the result of a failed endeavour to create a burglar alarm in Russia!
Mojo reckoned Queen were denigrating electronic options with the "No Synthesisers" notices on their first couple of albums. Queen were just making out out clever they were. No Synthesisers but Brian May had plenty of electronic hardware backing him up.
Walter (Now Wendy) Carlos had been releasing albums such as Switched On Bach done entirely on the Moog Synthesiser and came to prominence with his soundtrack to Stanley Kubrick's "A Clockwork Orange".
The us rockers were hit for six when Giorgio Moroder masterminded Donna Summer's "I Feel Love" . This was disco !! But it was good disco!!
Any I have missed lots out but I hope this makes you want to find out more. I've not mentioned Bowie , Jean Michel Jarre , Depeche Mode , Brian Eno , The Human League or Depeche Mode and I could fill another page or so with artists.
EMI's Electrospective here.