SS Imperator was an ocean liner built for the Hamburg America Line (Hamburg Amerikanische Paketfahrt Aktien Gesellschaft, or HAPAG), launched in 1912. Upon launch, she surpassed the just completed RMS Titanic by 24 ft (7.3 m), and she herself was surpassed the same year by SS Vaterland by 44 ft (13 m). She was the first of a trio of successively larger Hamburg America ships that included SS Vaterland and SS Bismarck built by the line for transatlantic passenger service. At the time of her completion in June 1913, she was the largest passenger ship in the world, surpassing Titanic's sister ship, RMS Olympic.