The Gladiators is the name of Arthur Koestler's novel about the Spartacus revolt in the Roman Empire. Although not as famous as Howard Fast's novel Spartacus (source material for for Kubrick's film), The Gladiators is interesting in its own right, because Koestler is not merely writing about the original slave revolt, but the 20th century left in Europe. Spartacus was an inspiration to Communists in Europe, and one group even named themselves the Spartacists in memory of him.

Koestler took the controversial view that one of Spartacus' companions was an Essene and that his views influenced the revolt, and the idea of the utopian "Sun City" which the revolt would found. The historical research is sometimes shaky, and the book contains a number of anachronisms, including fire escapes on Roman houses.

The book forms a trilogy with Darkness at Noon, and Arrival and Departure on idealism going wrong, a common theme in Koestler's work and life. Its arrival was timely, being written on the brink of World War II. It was originally written in Hungarian.