Stalin killed many more than Hitler.
But the greatest modern-day murderer is Chairman Mao. I’ve heard hundreds of thousands died at his hand.
“Bloodlands” agrees with you. A book about the killings in Central Europe in the Hitler-Stalin era. The grimmest history book I’ve ever read.
Including the Chinese who died from starvation due to Mao's Agricultural Mismanagement more like 50 million.
Then there was Genghis Khan, and his millions; Destruction_under_the_Mongol_Empire snip...
"The Mongol conquests resulted in widespread and well-documented death and destruction throughout Eurasia, as the Mongol army invaded hundreds of cities and killed millions of people. One estimate is that approximately 10% of the contemporary global population, amounting to some 37.75–60 million people, was killed either during or immediately after the Mongols' military campaigns.[8] As such, the Mongol Empire, which remains the largest contiguous polity to ever have existed, is regarded as having perpetrated some of the deadliest acts of mass killing in human history. "
Islamic-India-Holocaust world history
Then there is the centuries long holocaust by Islam in India which is totally overlooked by every modern liberal. The body count given was based on the boasting records left by the Muslim rulers themselves. (See the link for particulars.)
Snip....."The World seems to either ignore or just does not seem to care about the many millions of lives lost during the 800 – year long holocaust of Hindus, Sikhs and Buddhist in India.
The Indian historian Professor K.S. Lal estimates that the Hindu population in India decreased by 80 million between 1000 AD and 1525 AD, an extermination unparalleled in World history. This slaughter of millions of people occurred over regular periods during many centuries of Arab, Afghan, Turkish and Mughal rule in India.
I annoy people by arguing that if Hitler had not existed, Europe would still have had a bloodbath, from the USSR conquering it without real opposition. The demographics of the dead would have changed, but the total would likely be higher.