古斯塔夫·西奥多·霍尔斯特（英语：Gustav Theodore Holst，1874年9月21日－1934年5月25日），英国作曲家。原名为Gustav（Theodore）von Holst，在第一次世界大战后去掉了名字中的von。出生于音乐世家，祖先多为英国人，其余为瑞典人。19岁时，进入伦敦皇家音乐学院，师事查尔斯·威利尔斯·斯坦福五年。1906年后边担任伦敦圣保罗（St Paul）女子学校音乐系主任，边同时进行作曲。在音乐写作上，除大胆地进行和声的实验外，也采用多调的作曲手法。代表作为管弦乐组曲《行星组曲》（The Planets）。

Gustav Theodore Holst (born Gustavus Theodore von Holst; 21 September 1874 – 25 May 1934) was an English composer, arranger and teacher. Best known for his orchestral suite The Planets, he composed a large number of other works across a range of genres, although none achieved comparable success. His distinctive compositional style was the product of many influences, Richard Wagner and Richard Strauss being most crucial early in his development. The subsequent inspiration of the English folksong revival of the early 20th century, and the example of such rising modern composers as Maurice Ravel, led Holst to develop and refine an individual style.