The Fish Speakers are a fictional army from Frank Herbert's Dune universe, as depicted in the Dune series of science-fiction novels. Emperor Leto Atreides II created them between Children of Dune and God Emperor of Dune novels. They were led by the various Duncan Idaho gholas.

Leto II founded the Fish Speakers to enforce his rule over the known universe. He found the existing military organisations, the Fremen and the Sardaukar, unsuitable to his needs. Leto believed that male dominated military organisations were essentially predatory and would turn on the civilian population in the absence of an external enemy. He also needed a reliable religious organization to enforce what came to be known as Leto's peace to ensure the unfolding of the Golden Path.

The Fish Speaker army was entirely composed of women, with men playing no role in the lives of the Fish Speakers other than that of husband. Men were totally shut out of the Fish Speaker combat forces. Leto trained them to be fanatical, disciplined, and extremely effective soldiers and police. Leto used the Fish Speakers in his breeding program, taking advantage of their speed and strength.

With the exception of the nomadic Amazons who legend described as once ruling part of the Asian steppes of the Old Earth, the Fish Speakers were just about the only effective all-female army known throughout the history of the dune universe. They were also, in terms of worlds ruled and historical longevity, the most effective military force ever known.

After Leto died, control of the Fish Speakers passed to Duncan Idaho and Siona Atreides. By the time of Heretics of Dune, their influence had sigificantly waned in comparison to the Bene Tleilaxu, Ixians and Bene Gesserit. A Fish Speaker council controlled some areas of space that used to fall under Leto's rule.