I've been doing some research on holocausts. This is not a pleasant topic, but it is one of our era's inescapable realities.
Prior to the past century, there have been many other holocausts and genocides, with assaults on indigenous people and the engagement in slave-trading by European and Asian colonialists the most extensive over the past several centuries.
Here are the quick numbers for roughly the past century (and I don't believe you can get this in one place):
1. The Nazis/Fascists killed 17 million or more people prior to and during WWII. They targeted Jews, Poles, Slavs, Russians, Romany, disabled people and other social minority groups. The holocaust began with killings of disabled citizens and non-German babies, and spread from there. The intent to wipe Jewish people from the face of the earth was total.
2. The communists have killed 85-100 million, with Stalin responsible for the deaths of 10 million or more, and Mao having killed 40 million or more. The communists are noted for killing and imprisoning those who resist their totalitarian vision of centralized total state authority.
3. Not usually listed, but regrettably and most clearly also meeting the criteria for holocaust perpetration, the United States has left 20-30 million dead through military action and strategic arms sales since WWII. Americans target those who are identified as hostile to US interests and security, but the definition has been loose, and, repeatedly, American interventions have been extended, disproportionate and difficult to rationalize. Millions have died through US interventions in North Korea, Vietnam, Iraq, Afghanistan, East Timor, and 32 other identified nations. This estimate does not include the additional many millions displaced or dead through US actions that have destabilized their nations, initiated civil wars, etc. (Libya and Syria are important recent examples).
Currently, death tolls are mounting rapidly in various Muslim states, but, so far, only the Nazis, communists and Americans have created overt holocausts during the period of recent history.
To my eyes, Saudi Arabia is currently the most dangerous Muslim state, due to its high level of interventionism (mounting a genocidal war in Yemen, funding global terrorism and jihadism, etc.). US arms sales to the Saudis are $35 billion annually.
The US presently spends $1 trillion a year on military activities, surveillance operations and veterans' services. It is difficult to devote that much expenditure annually to such purposes without causing overt and widespread harm, and I believe that to be the actual and ongoing result of America's unfocused military and strategic adventurism.
Click here for more information on the US-initiated holocaust.