Harry O. Hoyt (6 August 1885 – 29 July 1961) was an American screenwriter and film director whose film career began in 1912, during the silent era. He graduated with a degree in literature from Yale University in 1910. His 1925 film The Lost World, based on the book by Arthur Conan Doyle, is notable as a pioneering effort in the use of stop-motion animation. His brother, actor Arthur Hoyt, also appeared in The Lost World.

In November 1912, he married the former Florence Stark in Norwich, Connecticut. Together they had a son, Devereux Gerrard Hoyt, and daughter Daryl Hoyt.