William Marshal (or William Leonard Marshal) (born 1944, Australia) is an Australian author, best known for his Hong Kong-based "Yellowthread Street" mystery novels.

In the Yellowthread Street series, the detectives of the Yellowthread Street police station in fictitious Hong Bay, Hong Kong -- DCI Harry Feiffer, a European born and raised in Hong Kong; Senior Inspector Christopher O'Yee, half-Chinese, half-Causasian American, and all neurotic; and the ever-bickering team of Inspectors Auden and Spencer -- attempt to find the rational basis for inexplicable and seemingly bizarre crimes. For example, in 1988's Out of Nowhere, DCI Feiffer must figure out why in the pre-dawn hours, four people in a plate-glass-filled van with Chinese opera blaring out the tape deck were driving on the wrong side of a deserted motorway, miles from the nearest on-ramp, before dying in a violent collision with an oncoming lorry. And why, moments before the collision, did one of the passengers shoot the van driver?

Marshall's novels manage to juggle violence, suspense, and slapstick humor in his twist on the police procedural form. He has also written two mystery series based in Manila and late-19th-century New York City, the latter featuring City Detective Virgil Tillman -- New York City's "first thinking detective" -- and his partner, patrolman Ned Muldoon of the Strong Arm Squad.

William Marshall...has worked as a playwright, journalist, proofreader, morgue attendant, and was a teacher in an Irish prison says the dust jacket of New York Detective (1990).

Novels

Yellowthread Street series

• • Yellowthread Street (1975)
  • The Hatchet Man (1976)
  • Gelignite (1976)
  • Thin Air (1977)
  • Skulduggery (1979)
  • Sci-fi (1981)
  • Perfect End (1981)
  • War Machine (1982)
  • The Far Away Man (1984)
  • Roadshow (1985)
  • Head First (1986)
  • Frogmouth (1987)
  • Out of Nowhere (1988)
  • Inches (1994)
  • Nightmare Syndrome (1997)
  • To The End (1998)

Manila Bay series

• • Manila Bay (1986)
  • Whisper (1988)

New York Detective series

• • New York Detective (1990)
  • Faces in the Crowd (1991)

Other Novels

• • The Fire Circle (1969)
  • The Age of Death (1970)
  • The Middle Kingdom (1971)
  • Shanghai (1979)