So many good answers already that I agree with. So I’ll add James Ellroy and Clive Barker

For Ellroy, the entire LA Quartet remains a pivotal sea change in “hard boiled” crime fiction; taking a lot of the conventions created by the likes of Hammett and Chandler and updating them for a modern audience.

Barker is a more personal choice. But his writing is just so evocative and descriptive that I couldn’t NOT mention him. Imajica literally changed my literary life, with Weaveworld being (in my opinion) a less dense, more reader friendly version of Imajica.