Fritz Zwicky, where do we start? I can't say I met him, did attend a talk by him, he died soon after my career began. His best work was done in collaboration with Walter Baade, who was a more down to earth character whose practicality harnessed the best of Zwicky's ideas, which ranged from the genuinely insightful to the downright bonkers. And these two between them realised that supernovae were the result of a collapse of a star at the end of its life, and that neutron stars were the end result. They were also the first to suggest that supernovae could be used as standard candles. Zwicky noticed that the motions of galaxies in the Coma cluster implied a much larger mass than could be accounted for by galaxies themselves, leading to later theories of dark matter. The expansion of the universe illustrates the difference between Zwick and Baade, Hubble discovered the correlation between redshift and distance, but his estimate of what we know as the Hubble Constant was much larger than the one we have today. Zwicky saw that the expansion implied was too large, and produced instead a "tired light" theory in which photons lost energy as they traveled through space. Baade spent the best part three decades making careful measurements of Cepheid Variable stars, which gave more accurate measurements of galaxy distances, and concluded that Hubble had overstimated his constant by a large factor, and that the expansion rate implied was reasonable.

Zwicky was known for his strong views, particularly about other people. If you get a chance, in a serious academic library, have a look at the text to his "CATALOGUE OF SELECTED COMPACT GALAXIES AND OF
POST-ERUPTIVE GALAXIES" (sorry for the caps that is a cut and paste) which is basically a tirade against most of the other leading astrophysicists of the day, including his long-time collaborator, Walter Baade.

Morphological analysis has its uses in Astrophysics even now, but taken outside this field I am not so sure. Zwicky had some great ideas, but some daft ones also.