奥斯卡·汉默斯坦二世（Oscar Hammerstein II，1895年7月12日－1960年8月23日），美国著名音乐人、歌词作家、音乐剧制片人、导演，曾同理察·罗杰斯合作，两次获得奥斯卡最佳原创歌曲奖。

汉默斯坦出生于纽约市的一个美国圣公会家庭，其祖父是著名美籍犹太人作曲家奥斯卡·汉默斯坦一世。汉默斯坦1912年进入哥伦比亚大学学习，1917年自哥伦比亚大学法学院退学，以追寻自己的音乐梦想。

1921年，汉默斯坦作词的首部音乐剧《Always You》在百老汇上演，其后他继续与制片人Otto Harbach和作曲家Jerome Kern合作多年，推出了多部音乐剧。

Oscar Greeley Clendenning Hammerstein II (/ˈhæmərstaɪn/; July 12, 1895 – August 23, 1960) was an American librettist, theatrical producer, and (usually uncredited) theatre director of musicals for almost forty years. Hammerstein won eight Tony Awards and two Academy Awards for Best Original Song. Many of his songs are standard repertoire for singers and jazz musicians. He co-wrote 850 songs. Hammerstein was the lyricist and playwright in his partnerships; his collaborators wrote the music. Hammerstein collaborated with composers Jerome Kern with whom he wrote Show Boat, Vincent Youmans, Rudolf Friml, Richard A. Whiting and Sigmund Romberg; but he is best known for his collaborations with Richard Rodgers, which include Oklahoma!, Carousel, South Pacific, The King and I, and The Sound of Music.