FamousPsycho chordPsycho, 1960 · Bernard Herrmann
Prelude (main title), bars 1–3: short syncopated stabs, sff on muted strings; it returns through the Prelude (which begins and ends on it) and closes the cue 'Marion'
A B♭ minor chord with an A added, played with F in the bass: B♭m(maj7)/F. It is the first sound of Psycho, hammered out as short, loud stabs by strings wearing mutes, so it is violent but choked. The A grinds a half step against the B♭ and Herrmann never lets it resolve, which keeps the whole title sequence on edge.
Also called Hitchcock chord, minor-major seventh chord
Sources: Pearson Edexcel A-level set-work guide, Herrmann: Psycho · Royal Holloway Teacher Hub, 'Bernard Herrmann's Film Music: Psycho and others' · Bill Wrobel, 'Chord Profile #2 (Psycho)' (from the written score)