The Sigillites were an ancient, secretive organisation of men and women present on Terra in the strife-ridden millennia before the appearance of the Emperor of Mankind and the start of the Unification Wars.
They were dedicated to the collection, rescue and protection of the greatest cultural artefacts in the history of Humanity, including ancient weapons technologies, from the chaos and tumult that afflicted Terra during the Age of Strife and destroyed Humanity's early interstellar civilisation.
According to their only known and perhaps last surviving member, Malcador the Sigillite, the Regent of Terra, they had existed during the Age of Technology even before Old Night had consumed the galaxy.
At some unknown time before the Emperor's rise, the Sigillites were disbanded or scattered, but their ancient fortress in the Himalazian (Himalayan) Mountains and the artefacts and knowledge they had managed to collect there became the foundation of what would later become the Imperial Palace.
Malcador had carried on the work of the Sigillites, seeking to preserve all the great artefacts of Human history.
Malcador took his byname of "the Sigillite" from his membership in the secretive group, though the Imperial public believed the Emperor had given the name to him to symbolise his position as the Master of Mankind's "seal-bearer" or regent.
Two of the treasures the Sigillites had once protected -- the ancient paintings Mona Lisa by Leonardo da Vinci and Sunflowers by Vincent van Gogh -- were Malcador's most prized possessions, proudly displayed in his personal quarters in the Imperial Palace.
- The Sigillite (Audio Book) by Chris Wraight
- Angels of Caliban (Novel) by Gav Thorpe, Ch. 18