RE: Stamler &c - Melodrama riffs or entrance music carried over from the vaudeville and silent film eras.

For the American types it was the Indian intermezzo Silver Heels. Still hanging on today as the “tomahawk chop” (aka: FSU Seminoles Indian War Chant)

Most folks 'of a certain age' might also recognize Mysterioso Pizzicato for villains; ghosts &c.