The Secret of Sinharat is a science fantasy novel by American writer Leigh Brackett, set on the planet Mars, whose protagonist is Eric John Stark.

The novel is expanded from the novella "Queen of the Martian Catacombs", published in the pulp magazine Planet Stories in the Summer 1949 issue.

In 1964, after considerable revision and expansion, it was republished as The Secret of Sinharat as one part of an Ace Double novel; its companion was another expanded Eric John Stark story, People of the Talisman.

[2] In 1982, it was published again, together with People of the Talisman, under the title Eric John Stark, Outlaw of Mars.

In 2008, the entire Eric John Stark saga was republished in E-Book form by Baen Publishing.