Heraclius II (Greek: Ηρακλειος Β')was Roman Emperor and Caliph of Islam from 795 to 859. He is known for having been the longest-ruling of all emperors to date, having reigned for 64 years in an era where the average life expectancy was barely 40, and for his efforts to avoid the total collapse of Roman power. He was raised to the imperial dignity amidst the troubles following the assassination of his half-brother, Constantine VI, and spent the first year of his reign hunting down the assassins and bringing the plotters, led by his stepmother Irene, to justice.