If you like campy humor mixed with your grimdark Dungeon Crawler Carl is one of the best things ever.

Could try some Warhammer 40k. Gaunt's Ghosts by Dan Abnett is a good series

It depends on what about grimdark appeals to you.

For ultraviolence: Acts of Caine by Matt Stover, especially the first book. Though this is maybe sci-fi?

For snobbery hoity toity book club cred: Shadow of the Torturer by Gene Wolfe

For ultimate chunk: The Malazan Cycle by Steven Erikson. I recommend reading with a wiki open. It's worth the struggle, but it IS a struggle to get started.