Off the top of my head when it comes to the genres I read the most:
-The Girl with the Dragon Tattoo. The nordic thriller genre was highly prolific well before it, at least since the 1960s, but Larsson popularised it to a wider non-Nordic public by introducing cartoonish, exaggerated, violent, movie-like elements that contrasted with the tradition both of Nordic thrillers and of crime novels in general, and formed the basis for many successful writers that came afterwards.
-Battle Royale. Pulp, extreme and theatrical, it is a landmark of dystopian fiction that IMHO deserves to be in the same realm as 1984 and Lord of the Flies (not necessarily in prose quality, but part of it is because it’s not in English originally and the translation is bad) and is perhaps the single most important work of the whole “killing game” sub-genre.
Argueably much of that was done earlier by robert jordan’s wheel of time which sanderson finished, but that was early 90s affecting.
The Wheel of Time made a massive impact on the fantasy genere. Arguably the biggest shift since LOTR. Sanderson has spoken about loving those books and rereading them endlessly as a kid. It might be too far to say Sanderson is a Jordan product as they never met. But the influence is hard to overstate.