Jan 5 Al-Mu'tasim, Abbasid caliph (b. 794) Jan 20 Theophilus, Byzantine kaiser (829-42), dies Mar 20 Alfonso II the Chaste, king of Asturia (791-842), dies 840 AD Famous Deaths by Year 843 AD Famous People by Cause of Death Assassination Drug Overdose Gunshot Wound Murder Plane Crash Suicide