Lisa Della Casa
She made several complete opera recordings including her singing of Countess Almaviva in Le nozze di Figaro (Erich Kleiber conducting) and the role of Arabella in Arabella (Georg Solti conducting).  These recordings are still thought of as among the finest ever made.  She made a wonderful recording of Richard Strauss' Vier letzte Lieder (Four Last Songs) (Karl Böhm conducting) in 1953.