Abd al-Hazir is a lore enthusiast and adventurer, scribing about a lot of his experiences in the world of Sanctuary. He is used as a tool for Blizzard to describe Diablo lore on the D3 webpage.
Abd al-Hazir is a renowned gentleman, historian, and scholar. He has recently taken up the unprecedented task of investigating, researching, and compiling information about the unique locales and denizens of our world.
On his travels, he have among other things travelled the Tardein wastes (desert close to Caldeum) and met Franklin Burroughs, the Dune Thresher-hunter.
Among his works he count the Xiansai Chronicles and the Writings of Abd al-Hazir.
It is unknown if he will be come a NPC in Diablo III or not.
Meta-Info
In OUR world, the meaning of "Abd" is literary "Worshipper of God" or "Worshipper" in Arabic, and "al-Hazir" mean "The Warner". The meaning of Abd al-Hazir would therefore be Worshiper of The Warner. Whether the Eastern countries of Sanctuary uses the same Arabic language as our own Earth is unknown, and we know that the character Abd is not very religious so the name might be unrelated, but we don't know how much homework Blizzard have done and they might actually use a lot more directly Arabic names and meanings in the game.
References
Almost everything known about Abd comes from his own writing: