"At the time leading organic chemists such as Emil Fischer and Heinrich Wieland believed that the measured high molecular weights were only apparent values caused by the aggregation of small molecules into colloids. At first the majority of Staudinger’s colleagues refused to accept the possibility that small molecules could link together covalently to form high-molecular weight compounds. As Mülhaupt aptly notes, this is due in part to the fact that molecular structure and bonding theory were not fully understood in the early 20th century.Keep in mind that this is the same Fischer who established the relative sterochemistry of sugars (and was lucky(!) enough to actually be correctly identify the absolute chemistry). Staudinger caught quite a bit of heat for a couple of decades for the whole idea of such large molecules as chemists were not comfortable with the idea, let alone the idea that a given polymer would have a distribution of molecular weights. (All that discomfort still exists today for many chemists. You've seen it, right? Chemists who just ignore polymers, despite the fact that many of them are trivial to synthesize.) And so that's the basis for my choice.
I briefly considered Paul Flory, as he was able to provide tremendous contributions to the science across a vast range of areas, both chemical and physical. And Carothers would be another option, somewhat appealing by the tragic life he lead, and being hounded by depression certainly requires courage that most of us cannot understand. And there are certainly others that have made important contributions, but on the basis of my (personal) definition of hero, I'm sticking with Staudinger.