The Archivist was Blizzard's 2009 April Fool's joke for a new class in Diablo III. A unique monster with the same name however, does make an appearance in the full game. In the short clip, the Archivist resembles the Deckard Cain model.
Short in-game video clips featured three of the Archivist's skills - Lorenado, Quest Bolt and Shush.
Two in-game screenshots and one concept art image were also displayed:
The following text appeared on the Archivist page at the official Diablo III website:
In my writings, I have recounted stories of the barbarians and their endless battles with the demons of the frozen north, and devoted pages to the wizards of Caldeum who harness the primal forces of reality. But the might of these heroes is nothing compared to the power of the archivists of Westmarch. These brave souls wade into battle wielding tome and quill, armored not in ensorcelled plate or links of chain, but in the knowledge of generations past. These archivists fight not only for our future, but for our past as well.
I first encountered an archivist in the ruins of the great city of Travincal. While exploring one of the long-abandoned temples, I was drawn by the flickering of faint torchlight through a distant doorway, and then, as I crept nearer, by the sound of a voice. There was a feeling in the air of danger near at hand, an electricity that made the hairs on my neck rise. I inched forward, breath caught in my throat, grateful for the safety of the hallway's long shadows. Then I saw him.
He was surrounded, the looming shapes of his foes bearing down upon him. His hair was unkempt and frazzled, his calloused hands cut and stained. But he had an air of supreme confidence, of a submerged violence that threatened to explode into being. He leapt forward, his hands grabbing for the leather bindings of his nearest enemy.
The archivist's eyes searched for an opening, a weakness. His hands wrenched suddenly about his adversary and a sickening crack pierced the still air. Its spine broken, the book lay unmoving in the archivist's now gentle grip. As he lifted its lifeless form into the dim light, the pages of the ancient tome fell open, the secrets of the text laid bare. I remember the words he read, the religious fervor of his voice: "Here begins the first chronicle of the life of holy Akarat, prophet of Zakarum...." And on the shelves that stood all around him, tome after tome waited.
I have the utmost respect for the archivists, these warriors of myth and legend. We know their names: Alimet Two Quills, master of illumination with both left and right hand; Morienne the Scrivener, a midwife whose poetry stole the hearts of kings and brought tyrants to tears; and Salazar Cid, the Master Transcriber of Gea Kul, whose bombastic penmanship is known in all the lands of the Twin Seas and beyond. But these are only a chosen few. The members of their honored fraternity are many, and their numbers grow every day.
In the dark days that I fear are yet to come, much will be decided by sword and axe, with steel and spell, but I believe that in scroll and tome our survival lies.