The answer to this question depends largely on your definition of what a hero is. By my definition, Stalin is most definitely not a hero.
It would be possible to say that Stalin was a true hero if you define a hero simply as someone who accomplishes notable things. Stalin certainly accomplished some important things. He was the ruler/dictator of the Soviet Union for over 20 years. During that time, he led the country through World War II, in which it did much of the work of defeating Nazi Germany. He forced the country to industrialize, taking it from a backwards economy to one that could at least compete with the US in terms of military power. Under his rule, the Soviet Union became one of the two most powerful countries in the world. This is notable, so if you think that a person can become a hero just by doing notable things, Stalin was a true hero.
However, in my mind, a hero is not just someone who accomplishes notable things. Instead, a hero has to be in some way noble and has to be morally admirable. We have to be able to look at a hero and say “I would want to have those qualities.” A hero also has to work for goals that we can applaud. If we look at things in this way, it is hard to call Stalin a true hero. It is true that he was driven and determined, and it is true that those are good qualities. However he was also extremely vicious, ruthless, and selfish. He killed or imprisoned millions of people simply for disagreeing with him or for being, in his mind, a threat to his power. He implemented policies that caused millions more to die of starvation. He had no compunctions about condemning people to death (either through execution or through overwork/starvation) in order to achieve the goals that he had set.
A hero (in my view) has to be someone who has good moral qualities and who pursues worthy goals in good ways. If we define a hero in this way, Stalin was not a hero.