The Elektra chord is a "complexly dissonant signature-chord"^[1] and motivic elaboration used by composer Richard Strauss to represent the title character of his opera Elektra that is a "bitonal synthesis of E major and C-sharp major" and may be regarded as a polychord related to conventional chords with added thirds,^[2] in this case an eleventh chord. It is enharmonically equivalent to a 7#9 chord : D♭-F-A♭-C♭-E and a 6b9 chord : E-G#-B-C#-F.

In Elektra the chord, Elektra's "harmonic signature" is treated various ways betraying "both tonal and bitonal leanings...a dominant 4/2 over a nonharmonic bass." It is associated as well with its seven note complement which may be arranged as a dominant thirteenth^[1] while other characters are represented by other motives or chords, such as Klytämnestra's contrasting harmony. The Elektra chord's complement appears at important points and the two chords form a 10-note pitch collection, lacking D and A, which forms one of Elektra's "distinctive 'voices'"^[3]

The chord is also found in Claude Debussy's Feuilles mortes, where it may be analyzed as an appoggiatura to a minor ninth chord, and Franz Schreker's Der ferne Klang, and Alexander Scriabin's Sixth Piano Sonata.^[2]