Otto Hamacek (1 October 1896 – 26 March 1984) was an Austrian football player and coach.
As player he was a midfielder and played with SK Rapid Wien in the 1923–24 Austrian championship.
He played for the Vienna selection team in 1919 representing Rapid.Later he became a coach and managed Swiss top-flight side FC Luzern between February and summer 1929 and Yugoslav side FK Vojvodina in the season 1931–32.