The Lion Helm is an ancient and revered artefact that takes the form of an angelic-winged helm, said to have once been worn by the Dark Angels' Primarch Lion El'Jonson during the bygone days of the Great Crusade and the Horus Heresy over ten thousand standard years ago. It is now the primary badge of office of the current Supreme Grand Master of the Dark Angels. As with all heirlooms connected to the mighty Primarch of the Dark Angels, it is attended by the mysterious Watchers in the Dark, one of the strange race of creatures which inhabit the Chapter's mobile fortress-monastery, known as the The Rock. The helm generates a powerful force field that has protected the Supreme Grand Master since the days when the Dark Angels were still a Space Marine Legion, in a similar way that an Iron Halo would. To don that winged helmet is to take up the mantle of the Lion and lead the Dark Angels to victory, or die in the attempt.
- Codex: Dark Angels (6th Edition), pp. 23, 52-53, 70, 92
- Codex: Dark Angels (4th Edition), pp. 46-47, 60
- Codex: Dark Angels (3rd Edition), pp. 2, 17-18
- Codex: Angels of Death (2nd Edition), pp. 13, 41, 62
- Warlords of the Dark Millennium: Azrael (Digital Edition)