Yes, Vladimir Lenin should be viewed as one of the 20th century's greatest monsters, because he was responsible for the deaths of so many people. While saying otherwise, Lenin was fine to sit by while his people starved and suffered. He did little to save the people that he ruled over. His rule was one of terror.
He might be famous and loved by some in Russia for ending the monarchy, but he did so by having the Tsar Nicolas and his family murdered. I don't consider that the act of a moral person. He didn't end up being any better than the regime of the Tsar. He ordered the killing of countless amount of people during his reign as well.
As early as the 1905 Revolution Vladimir Lenin is was known to hold up violent measures to meet an end including urging Bolsheviks to increase unrest. This support of violence followed Vladmir Lenin during his lifetime, so in my personal opinion, he could be considered a tyrant. I think that term is more fitting than monster.
Funny how some ignore the White Terror, Tsarists were not afraid to volley into women and children, in in the Bloody Sunday Massacre. Lenin caused the literacy rate to skyrocket, legalized homosexuality (till Stalin caused a shitstorm after Lenin died) and far increased the standard of Lenin. His methods were dark and blood stained but he was a man who sought ends.
Lenin was by no means a saint and a lot of the things he did was unjustifiable and disgusting, but I do think there was a lot of positives done under the leadership of this man. The real monster was his successor, one Joseph Stalin. The focus is very off here.
Those who survived under the reign of Vladimir Lenin are certainly convinced he deserved to be on the list of 20th century greatest monsters. However, from an external perspective that would have to be a long list. The 20th century has seen quite a few 'monsters,' and not all of them were leading a country. Machiavelli would say that Lenin acted as was necassary for success in the war.