A Warhammer 40K character who is the Primarch of the XIIIth Legiones Astartes, the Ultramarines. A master strategist and administrative figure, his Legion was one of the largest to the lead up of the Horus Heresy. In recent lore, he was awoken from stasis within the Ultramarines' Fortress-Monastary and has become the de facto leader of the Imperium of Man, attempting to hold it together after the galaxy was split in two by the Cicatrix Maledictum at the wake of Abaddon's 13th Black Crusade and the Fall of Cadia.
Fans will often give him nicknames such as "Rowboat Gill-man", "Big Bobby G" or "Girlyman" given the difficulties in correctly spelling or pronouncing his name, and he has been periodically shipped with an Eldar named Yvraine due to her role in his resurrection.
(Text taken from https://wh40k.lexicanum.com. Tags added.)
It is known that at the height of his power during the Horus Heresy, Guilliman was armed with the Hand of Dominion — a mighty power gauntlet[13] that with Guilliman's strength could fell a Titan[14], the Gladius Incandor — a blade of exceptional craftsmanship and a symbol of his Legion and also - with an Arbitrator, a customised combi-bolter.[13] For protection, Guilliman wore a suit of Power_Armour known as the Armour_of_Reason.[15]
Upon his resurrection at the end of the 41st Millennium Guilliman continued to use the Hand of Dominion but took up the Emperor's_Sword as his primary weapon. In addition, he now wears the Armour_of_Fate, the very device that allowed him to heal the injuries sustained by Fulgrim ten thousand years earlier.