Word Bearers were the XVII Legion of the Legiones Astartes, led by Lorgar Aurelian – a fanatical preacher who believed in the divinity of the Emperor. They hailed from the planet Colchis, where Lorgar was worshipped as a prophet. Their original names were Imperial Heralds and later Iconoclasts.

After their temples were destroyed by the Emperor, the Word Bearers turned to Chaos Undivided and became the first traitors. They established secret lodges within other Legions, planting the seeds of heresy. Units like the Gal Vorbak became the first daemonic Space Marines, while their Dark Apostles spread the Primordial Truth – the truth of Chaos.

In the Horus Heresy system, the Word Bearers have access to Diabolists and abilities like Dark Channeling and Rites of Possession. Their forces include Gal Vorbak, Ashen Circle, Blade-slaves, and heroes such as Erebus, Kor Phaeron, and Lorgar himself.