Answer
Horst Wessel, a member of the Nazi Party (NSDAP) and the Sturmabteilung (SA), is specifically identified as the author of the Horst-Wessel-Lied, the official anthem of the NSDAP. He wrote the lyrics in 1929 to commemorate the death of a fellow SA member. The song gained popularity within the Nazi movement and was eventually adopted as the party's anthem in 1933.