"Stalin" was a name chosen in the days before the so-called October Revolution; so-called as it actually took place in November according to the modern calendar subsequently adopted. It means "steel", as all or most now know. I suppose that makes him the first Man of Steel. The other one, a/k/a "Superman", was created in 1933 according to the invaluable Wikipedia--by high school students in Cleveland.
Stalin was, once, something like a high school student himself. He was once other things as well, before he became Stalin. He wrote romantic poetry in his native Georgian about his native Georgia, which it seems was considered rather good (the poetry, I mean). A romantic boy he may have been. He was not a romantic man, however. He was once a Georgian patriot, and came to be against Georgian nationalism, indeed nationalism of all kinds which endangered the unity of the Soviet Union. In fact, he came to extol Russians over the members of other nationalities subsumed by the Soviet Union. He was a seminarian who came to believe in God, if he did believe in God, as something no seminarian would recognize as God.
Whatever he was, he came to be a monster, though not a mere monster as sometimes maintained. He was often underestimated by Lenin, by Trotsky and others in the party and out of it, it seems to their regret. He survived them all. Sometimes he survived them by being responsible for their deaths, sometimes their imprisonment in the Gulag, sometimes he simply rendered them harmless or made them puppets of his will. He never forgot a sleight and rejoiced in destroying those who thought him a lesser man or lesser intellect.
Lenin was a special case. Stalin wouldn't hesitate to disagree with him even while he was alive. Lenin even criticized Stalin and warned that he was inclined to accumulate power, but he criticized Stalin's great rival and enemy, Trotsky as well. It seems Stalin admired and respected Lenin in some ways, but in any case knew that he had become a totem of Marxism, the Revolution and Bolshevism and in that respect could not be challenged. Lenin also conveniently died in the 1920s, while Stalin was on the rise but not yet claiming the summit of power.
All evidence indicates that Stalin was a highly intelligent man, and I think we underestimate him still by thinking him to be "only" evil. We tend to attribute evil to the Devil, or upbringing and environment, or psychological deficiencies. But people do evil things not just because they're bad, or immoral, due to some inherent defect or by being influenced by a malevolent supernatural power.
Stalin was even cultured, in his own peculiar way and patronized certain writers, again in his own peculiar way, rebuking them when he thought appropriate. He was not known as a great political thinker, but he read extensively. He worked very hard. He was a very able negotiator, as became known to the Western powers during and after the Second World War.
It's an amusing exercise to compare great tyrants and despots. Napoleon had his own romantic youth, and was an ardent Corsican patriot, but turned away from such childish things. Corsica became as unimportant to him as Georgia became to Stalin. Napoleon had no artistic pretensions, so far as I know, though like Stalin he had his favorite artists. He was an enormously hard worker and read constantly. He had a vast memory and formidable intellect. Goethe famously said Napoleon was as intelligent as a man could be without wisdom, and as great as a man can be without virtue.
Hitler was a failed artist, but it seems he differed from Stalin and Napoleon in various respects. He wasn't a hard worker, and may be called lazy in comparison. His intellect doesn't seem to have been impressive. And yet he's credited by such as B.H. Liddell-Hart with insight into military tactics and as being behind the Blitzkrieg and an astute proponent of the "indirect approach" to strategy, for a time, at least. Before his descent into madness or drug-induced irrationality and mania.
All three men were alike in their ruthlessness, though, in pursuit of their goals. That much seems clear. The ruthlessness of Stalin and Hitler is particularly striking and horrifying because in pursuing their goals they sanctioned the deliberate and coldly planned death of millions. Napoleon's wars caused a great deal of death and suffering as well, but Stalin and Hitler inflicted death not merely in war, but even more in the pursuit of ideological ends.
There is a difference, I think, between war and the planned annihilation of millions apart from war to achieve ideological or other ends. Stalin was responsible for the deaths of millions through starvation and by other means in the effort to modernize industry and collectivize agricultural production in the Soviet Union. He was responsible for the deaths, incarceration, persecution of peasants, kulaks, Cossacks, professionals and intelligentsia, all of which he deemed necessary under Marxist-Leninist theory. It seems evident that he sincerely believed what he did was required in order to make the Soviet Union a great power and in the pursuit of the goals of the October Revolution. While he was a vengeful man, it's not the case that he killed only because of personal hate or animosity or to achieve absolute power.
The fanatical pursuit of ideological goals regardless of consequences to others is far more destructive than hate or ambition, particularly where fanaticism is combined with ability. Stalin was a fanatic and a talented one. There's no doubt that he hated many within the party and wanted absolute power over it and the Soviet Union itself but he is truly monstrous because he was a true believer, and as such he thought that those who didn't believe as he did should be destroyed.