The album that got me into hip hop:
I’d been to see Terminator 2 at the cinema, and liked John Connor’s Public Enemy t-shirt (I was 13, okay).
Bought their latest release on cassette, on a whim. It was like nothing I’d heard before - so vital.
Loved it then, still love it now (still think that it’s the best PE album).
Liquid swords got me into hip hop
Mbv was shoegaze
Angel dust and reign in blood got me back into metal
Crooked rain crooked rain got me into all that American indie stuff
New slang was indie
Blueprint was fugazi mainly for ages and then loads of punk
Break stuff was nu metal
Concrete schoolyard was hip-hop
Lucy in disguise was vaporwave
Slam by pendulum was d+b
Maybe sunburn by muse was the start of all of it
Quite the twist ending there!
Got me into Wu Tang music
I was going to mention ISIS getting me into more extreme music and harsh vocals but @Scagden has that covered! 
So I guess once ISIS had got me over my resistance to harsh vocals then Diadem of 12 Stars by Wolves In The Throne Room can be thanked for getting me into black metal, especially the atmospheric, nature oriented sub-genres.
Green Day got me into punk for sure. Until then it was 100% British indie, and often not very interesting stuff either. I was just reliant on whatever the NME featured that week or who was on Top of the Pops. I seem to remember being a huge fan of Space for a while. This was the early days of the internet for me and it took me on a winding path into more pop punk stuff (Fat Wreck bands, Epitaph etc), backwards to 1977 with the Sex Pistols and the Clash et al, forward to US hardcore, from there post hardcore and Fugazi, At the Drive In, Husker Du, Dinosaur Jr, hitting Nirvana on the way and every band who influenced Nirvana, grunge, stoner rock. The whole musical map from there is amazing how it all links up, just from me hearing Basket Case one day and finding it more exciting than a new Suede single.
Descendents - Hallraker: Live!
I’m pretty sure this got me into punk. It was 92 or 93, my best friend at the time found this tape (without case) in the school parking lot and picked it up, not knowing what it was. We tossed it in the tape deck of my mom’s car (without my mom) and started driving around town as we did. Fell in love with it right away, it blew our minds and we had so much fun driving around with it. It didn’t leave the tape deck for weeks. To this day I still prefer a lot of the live versions from this to the studio ones, since I heard these first and made memories with them. This friend and I were into metal and hard rock at the time, it’s likely I’d already heard some Misfits as I do recall we were huge fans of Metallica and obviously knew the Garage Days covers and Cliff’s often photographed Misfits shirt. But it didn’t kick me off into punk the way Descendents did. The Misfits songs Metallica covered were still kinda metal to me, or at least didn’t feel like a completely different thing. I probably started to explore the rest of Misfits’ stuff around the same time we discovered Descendents, but this was the true springboard.
Soul jazz tropicalia compilation…
I was quite straight laced, Brit rock type guy before this, bought on a whim for no really reason other than I liked the cover and I liked the write up pinned to it in the record store.
Since them, never ending rabbit hole of sounds of world music (does it count as a genre??) But yeah it still stands as one of the best compilations of all time and a gateway to the sounds of South America.
Lemonheads version of Mrs Robinson and Shame about Ray saw me move into indie; Suede then cemented that move - was listening to stuff like Simple Minds, Tears for Fears, Deacon Blue before then (and still do)
Then a friend gave me a C90 with dubnobasswithmyheadman on and that took this indie-kid into electronica…
A Love Supreme by Coltrane was my entrypoint into Jazz a few years after that
idk, but it feels very DiS to confine it to an album
mostly songs and radio shows for me
O Brother Where Art Thou soundtrack. Planted a seed that grew into a pretty all encompassing musical passion that has defined huge parts of my life.
In 1987, Bon Jovi was my first entry in hard rock because they were the biggest band in America that specific year. I wondered how a band could reach such status whereas nobody had ever heard of them in Europe.
Dig Your Own Hole.