Was joseph Stalin a dictator?
Yes Stalin was a dictator.
After the revolution the USSR was a democratic communist state but the elite took control of the state and it became another oligarchy like any other. The first dictator of communist Russia was Lenin but when he died Starlin took over. Stalin was an imperialist as well as a dictator which is against the ideology of communism.
For this reason communists distance their views from those of Stalin as he only used communist propaganda to remain as head of state.
However it can be argued that Stalin was not entirely a dictator as he was unable to gain complete power in the USSR. He was never technically head of government and he could still be removed by legal means if anyone challenged the regime. This almost occurred in 1934 just before the Kirov Affair, with Kirov seeming to be a realistic candidate to take the post of general secretary from Stalin.
There was also brutal opposition to many of his policies including collectivisation and his attacks on the church, and in the later case he even abandoned his policy against the church during the second world war to further patriotism. He was unable to gain full control.