"The greatest and most convincing writer of invented worlds that I have read." —J.R.R. Tolkien

The Mezentian Gate is a fantasy novel by English writer E. R. Eddison, third in his Zimiamvian Trilogy. It is primarily a history of the rule of the fictional King Mezentius (the Tyrant of Fingiswold), and his methods of gaining and holding the Three Kingdoms of Fingiswold, Meszria, and Rerek in sway.

Published posthumously, The Mezentian Gate is only partially completed as prose. In many of the central chapters, only the plot outline is presented. The first edition, published in 1958, comprised those chapters completed by Eddison, supplemented by an  Argument summarizing the unfinished portions of the novel.

Includes an Introduction by James Stephens.