Stalin coined the term Marxism-Leninism. Marxism-Leninism was already in practice in Lenin’s time, though Lenin didn’t say his application of Marx’s theories was Leninist, the same way Marx didn’t call himself a Marxist. It was only after the fact that Stalin synthesized Marxism-Leninism by combining Lenin’s and Marx’s theories. In the same way, people didn’t call themselves Hegelians or Darwinians when Hegel and Darwin were alive.