Ibn `Adi is the Imam, the keen hadith Master who travelled the world, Abu Ahmad `Abd Allah ibn `Adi ibn `Abd Allah ibn Muhammad ibn Mubarak ibn al-Qattan al-Jurjani, the author of al-Kamil fil-Jarh wal-Ta`dil in five large volumes.
He was born in 277 H. The first he heard hadith was in 290 and the first he travelled was in 297.
He heard Bahlul ibn Ishaq al-Tannukhi, Muhammad ibn `Uthman ibn Abi Suwayd, Muhammad ibn Yahya al-Marwazi, Anas ibn al-Salam... al-Nasa'i... al-Firyabi... Abu Ya`la al-Mawsili... al-Baghawi... Ibn Khuzayma, etc.
He lived a long time and his chain of transmission became quite short. He specialized in narrator-criticism, hadith authentication and criticism, until he became a foremost expert in this science despite weakness in his grammar as one can gather from reading him.
Al-Daraqutni praised his book as sufficient for knowledge of the weak narrators. Ibn `Asakir and others declared him trustworthy and praised his mastership and memorization.
Apparently he was Shafi`i and compiled a book based on the chapter-headings of al-Muzani's Mukhtasar.
His method in the Kamil is to mention every narrator that was ever criticized, rightly or wrongly. Al-Dhahabi integrated it into Mizan al-I`tidal and expanded upon it, criticizing him at times for citing undeserving entries.
He died in 365. Allah have mercy on him.
al-Dhahabi, Siyar A`lam al-Nubala' (16:154).