estimates place 80-120 million deaths under 20th-century communist regimes, including democide, gulags, and famines like the great leap forward (45m) and holodomor (3-7m).
black book of communism (94m total).
https://www.hup.harvard.edu/books/9780674076082
death by government by r.j. rummel (118m total).
https://www.hawaii.edu/powerkills/DBG.CHAP1.HTM