The Forever War (1974) is a military science fiction novel by American author Joe Haldeman, telling the contemplative story of soldiers fighting an interstellar war between Man and the Taurans. It won the Nebula Award in 1975, and the Hugo and the Locus awards in 1976. Forever Free (1999) and Forever Peace (1997) are, respectively, direct and thematic sequel novels. The novella A Separate War (1999) is another sequel of sorts, occurring simultaneously to the final portion of The Forever War. Informally, the novels compose The Forever War series; the novel also inspired a comic book and a board game

William Mandella is a physics student conscripted for an elite task force in the United Nations Exploratory Force being assembled for a war against the Taurans, an alien species discovered when they apparently suddenly attacked human colonists' ships. The UNEF ground troops are sent out for reconnaissance and revenge.

The elite recruits have IQs of 150 and above, are highly educated, healthy and fit. Training is gruelling – first on Earth, in Missouri, and later on a fictional planet located beyond Pluto's orbit called "Charon". Several of the recruits are killed during training, due to the extreme environments and the use of live weapons. The new soldiers then depart for action, traveling via interconnected 'collapsars' that allow ships to cover thousands of light-years in a split second. However, traveling to and from the collapsars at near-lightspeed has massive relativistic effects.