Covenant languages

The Covenant has their own unique language, which is heard in Halo: Combat Evolved. In Halo 2, their words are translated for the convinience of the player. Elites in Halo 1 spoke a deep, warbling tongue. This was achieved by playing in reverse the voice acting of David Scully. The ever popular "Wort wort wort!" shouted by many Elites during gameplay is actually "Go go go!" reversed.

Written Language
Conversations from the Universe contains letters written by the Prophets of Truth and Supposition. The writing in these letters resembles English, with various alterations.