Stephen King recommendations:
Peter Straub (obviously, since he has done a couple of collaborations with him)
Neil Gaiman (Ocean at the End of the Lane, Neverwhere, American Gods)
Crime recommendations:
Dennis Lehane (could try the start of the Kenzie & Gennaro books - A Drink Before the War)
Don Winslow (The Power of the Dog, for example)
George V. Higgins (elegantly-written Boston underworld crime with plot mostly revealed through dialogue)
James Sallis (John Turner trilogy, for example, starting with Cypress Grove)
Daniel Woodrell (the Bayou trilogy, for example)
James Carlos Blake (for example, The Rules of Wolfe)
All of the above crime novelists are American and the last three (and possibly Winslow) are what I would call modern American noir.