Helmut Sick (10 January 1910 - 5 March 1991), was a German-Brazilian ornithologist.
A prominent ornithologist in Brazil, Sick published more than 200 papers, including his most influential work: Ornitologia Brasileira, Uma Introdução (1984), later translated into English as Birds in Brazil: A Natural History (1993). He also led scientific expeditions in remote areas in Brazil and described several species of birds, including the Brasília Tapaculo, Long-tailed Cinclodes, Stresemann's Bristlefront and Golden-crowned Manakin.