Károly Aggházy, or Aggházy Károly ['?kha?zi 'ka?roj] in Hungarian order (30 October 1855 in Budapest – 8 October 1918 in Budapest) was a Hungarian piano virtuoso and composer.
Aggházy was a pupil of Robert Volkmann, Anton Bruckner, and Franz Liszt.
He later taught at the National Conservatory in Budapest.
Besides several operas, most notably Maritta (1895), he chiefly wrote chamber music and pieces for piano.