Agnes Stavenhagen (3 September 1860 – 30 September 1945), pseudonym Agnes Denis, was a German operatic soprano. Through her work at the Weimarer Hoftheater and in concerts throughout Europe, she was a highly esteemed Kammersängerin and achieved great popularity during her lifetime. She was soprano soloist in the first performance in Munich of Mahler's Second Symphony in 1900, conducted by the composer.