The UN says violence suffered by civilians in Iraq "remains staggering", with at least 18,800 killed between 1 January 2014 and 31 October 2015. 36,245 wounded and some 3.2 million people have also been displaced internally over the same period. The UN says the figures of are conservative estimates and could be much higher. The latest figure will also certainly be much higher than the UN reports, because there are many no-go areas for activists and journalists.
The UN accuses so-called Islamic State of systematic and widespread violence, including holding some 3,500 mainly women and children as slaves. Followers of other religions have also been singled out - with Yazidis and Christians taking the brunt of summary executions and murders.
The report also documents alleged violations, including abductions and unlawful killings, by government forces, militiamen, members of the paramilitary Popular Mobilisation forces and Kurdish Peshmerga fighters.
UN High Commissioner for Human Rights Zeid Raad Al Hussein said the report "starkly illustrates what Iraqi refugees are attempting to escape when they flee to Europe and other regions. This is the horror they face in their homelands". Mr Hussein said the "obscene" casualty figures did not fully reflect the suffering of civilians as many had died "from the lack of access to basic food, water or medical care".