This thread is great!
For me, there was definitely a SINGULAR moment that made me want to pick up a guitar and play...
I was born in 1968 and listened to all the regular radio rock, with particular interest in the harder stuff, along with any albums my youngest uncle brought into my grandma's house.
Loved Priest, The Stones, Black Sabbath, Nazareth, Mountain, ELO, The Doors, Pink Floyd, etc.
Then, someone in school gave me a copy (and I do mean copy

) of "No Life Til Leather".
Sound quality was shit, but I can still remember thinking " I don't know what the hell this is, but I want to do it!"

....and I want MORE!
That crappy quality cassette was a game changer for me.
Specific Albums that molded me:
Metallica, everything
Anthrax, everything
S.O.D Speak English or Die
Slayer Reign in Blood
Judas Priest everything, but especially the early stuff
Pink Floyd anything Gilmore plays on
Iced Earth Something Wicked This Way Comes
Pantera everything
There is a lot more that I am influenced by in one way or another too.