Three Accidents That Enriched The Guitar Driven Sound Of Rock n Roll:

1961: Dick Dale and Leo Fender invent the reverb surf guitar sound:

Leo Fender kept giving Dale amps and Dale kept blowing them up! Till one night Leo and his right hand man Freddy T. went down to the Rendezvous Ballroom on the Balboa Peninsula in Balboa, California and stood in the middle of four thousand screaming dancing Dick Dale fans and said to Freddy, I now know what Dick Dale is trying to tell me. Back to the drawing board. A special 85 watt output transformer was made that peaked 100 watts when Dale would pump up the volume of his amp, this transformer would create the sounds along with Dale's style of playing, the kind of sounds that Dale dreamed of. BUT! they now needed a speaker that would handle the power and not burn up from the volume that would come from Dale's guitar.

Leo, Freddy and Dale went to the James B. Lansing speaker company, and they explained that they wanted a fifteen inch speaker built to their specifications. That speaker would soon be known as the 15'' JBL -D130 speaker. It made the complete package for Dale to play through and was named the Single Showman Amp. When Dale plugged his Fender Stratocaster guitar into the new Showman Amp and speaker cabinet, Dale became the first creature on earth to jump from the volume scale of a modest quiet guitar player on a scale of 4 to blasting up through the volume scale to TEN! That is when Dale became the 'Father of Heavy Metal' as quoted from Guitar Player Magazine. Dale broke through the electronic barrier limitations of that era!

1964: Dave Davies of The Kinks invents grunge sound while recording "You Really Got Me":

The influential distortion sound of the guitar track was created after guitarist Dave Davies sliced the speaker cone of his guitar amplifier with a razor blade and poked it with a pin. The amplifier was affectionately called "little green," after the name of the amplifier made by the Elpico company, and purchased in Davies' neighbourhood music shop, slaved into a Vox AC-30. link

1965: Roger McGuinn accidently invents the "jingle-jangle" guitar sound of The Byrds:

While 'tracking' The Byrds' first single, 'Mr. Tambourine Man', at Columbia studios, McGuinn discovered an important component of his style. 'The 'Rick' [Rickenbacker guitar] by itself is kind of thuddy,' he notes. 'It doesn't ring. But if you add a compressor, you get that long sustain. To be honest, I found this by accident. The engineer, Ray Gerhardt, would run compressors on everything to protect his precious equipment from loud rock and roll. He compressed the heck out of my 12-string, and it sounded so great we decided to use two tube compressors [likely Teletronix LA-2As] in series, and then go directly into the board. That's how I got my 'jingle-jangle' tone. It's really squashed down, but it jumps out from the radio. With compression, I found I could hold a note for three or four seconds, and sound more like a wind instrument. Later, this led me to emulate John Coltrane's saxophone on 'Eight Miles High". Without compression, I couldn't have sustained the riff's first note.' link.

[added, a fourth]:
1966: Eric Clapton combines the Gibson Les Paul and the Marshall Amplifier: link