What were the melodies or fragments of melodies used by wagner to identify particular characters, objects, or ideas called?

Leitmotif

Explanation:

  The term Leitmotif, which can be translated as a “driving motive”, consists of a theme or musical idea that constantly appears throughout a work in order to associate it with a character, object or idea.

   Although he never specified such a term, the leitmotif technique became known to Richard Wagner who systematically applied it to his operas. Later, the use of leitmotiv also became part of other languages, such as cinema and soap operas.