Ethel Lina White.
A word of praise today for author Ethel Lina White (1876-1944), most famous for The Wheel Spins (1936) and Some Must Watch (1933). These were both adapted for film: the former into Hitchcock's The Lady Vanishes (1938) with Michael Redgrave and Dame May Whitty, and the latter into Robert Siodmak's The Spiral Staircase (1945) with Dorothy McGuire, George Brent, and Ethel Barrymore. For the film, The Spiral Staircase's setting was changed to early-twentieth-century New England, but not one whit of its nail-biting plot about a serial killer stalking women is diminished. (Remakes appeared in 1961, 1975, and 2000).
The characters Charters and Caldicott, who debuted in The Lady Vanishes, also appear in Night Train to Munich (1940), Crooks Tour (1941), Millions Like Us (1943), and the TV series Charters & Caldicott (1985). Iris Carr in The Wheel Spins inspired K. K. Beck's smart flapper sleuth Iris Cooper (Death in a Deck Chair, Murder in a Mummy Case, Peril Under the Palms).
Sadly, with the exceptions of The Lady Vanishes, Some Must Watch, and While She Sleeps, the rest of White's suspense work is out of print. This includes Midnight House (aka Her Heart in Her Throat, 1942), filmed as The Unseen (1945) with Joel McCrea and Gail Russell and scripted by Raymond Chandler. Go here for a list of White's work.