Hetty Wainthropp Investigates is a British crime drama television series, starring Patricia Routledge as the title character, Henrietta "Hetty" Wainthropp, that aired for four series between 3 January 1996 and 4 September 1998 on BBC One. The series, spawned from a pilot episode entitled "Missing Persons" aired by ITV in 1990, was co-created by writers David Cook and John Bowen, co-starred Derek Benfield as Hetty's patient husband Robert, and Dominic Monaghan as her assistant and lodger Geoffrey Shawcross. It marked Monaghan’s acting debut.

Other co-stars in the series include John Graham Davies as local chief of police DCI Adams; Suzanne Maddock as Janet Frazer, a feisty young auto mechanic; and Frank Mills as Robert's brother Frank. In the United States, episodes have broadcast as part of PBS's anthology series Mystery!. A parody of the series, entitled Wetty Hainthropp Investigates, aired on 12 March 1999 as part of the Comic Relief telethon starring Victoria Wood, Julie Walters and Duncan Preston.