Ender's Game is a 1985 military science fiction novel by American author Orson Scott Card. Set at an unspecified date in Earth's future, the novel presents an imperiled humankind after two conflicts with an insectoid alien species they dub "the buggers". In preparation for an anticipated third invasion, Earth's international military force recruits young children, including the novel's protagonist, Andrew "Ender" Wiggin, to be trained as elite officers. The children learn military strategy and leadership by playing increasingly difficult war games, including some in zero gravity, where Ender's tactical genius is revealed.

The book originated as a short story of the same name, published in the August 1977 issue of Analog Science Fiction and Fact. The novel was published on January 15, 1985. Later, by elaborating on characters and plotlines depicted in the novel, Card wrote additional books in the Ender's Game series. Card released an updated version of Ender's Game in 1991, changing some political facts to account for the then-recent dissolution of the Soviet Union and the end of the Cold War. The novel has been translated into 34 languages.

Reception of the book has been mostly positive. It has become suggested reading for many military organizations, including the United States Marine Corps. Ender's Game was recognized as "best novel" by the 1985 Nebula Award and the 1986 Hugo Award in the genres of science fiction and fantasy. Its four sequels—Speaker for the Dead (1986), Xenocide (1991), Children of the Mind (1996), and Ender in Exile (2008)—follow Ender's subsequent travels to many different worlds in the galaxy. In addition, the later novella A War of Gifts (2007) and novel Ender's Shadow (1999), plus other novels in the Shadow saga, take place during the same time period as the original.

A film adaptation of the same name, written for the screen and directed by Gavin Hood, and starring Asa Butterfield as Ender, was released in October 2013. Card co-produced the film. The novel has also been adapted into two comic book series.