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.
Vladimir Lenin starved much of the peasantry in the Russian Famine of 1921-22 in the Volga and Urals River Regions in retaliation for revolts against his Bolshevik Army who were stealing food and supplies from the Kulaks (Land Peasants) who did not support or had nothing left to give these violent thugs. In part they reduced the amount of food grown only to supply themselves or their hamlet as they were never compensated for what was taken. So no extra food was grown for the larger regions as a whole or the cities. Lenin then ordered all food to be taken from the Kulak's homes and all grain for growing to be removed as punishment and that meant everyone starved. Lenin effectively murdered 1.5 million people and this was before he even really got started. Lenin was a megalomaniac who believed everyone was expendable to his cause as is proof with the 1918 Red Terror that saw thousands tortured, and mass killings. He also helped establish the GULAG system as early as 1919. Lenin's psychopathic rabid dog Stalin who was just a vicious criminal would never have gained any power if not for Lenin and so Stalin went on to finished the job killing roughly 18 million of their own people. Together they made Hilter look like he had dropped the ball.
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.