Antifa (Antifaschistische Aktion) under that name started in 1932 as action by the KPD to organise widest possible front against the nazis, in the face of SPD as a party being very reluctant to act against nazis. Many SPD members did joined, but as we know, their own party in reichstag made that futile.

Of course antifascist resistance is about as old as fascism or even older considering protofascists activity even before Mussolini coined the term, but the name itself is from 1932 KPD.