Erwin Schrödinger is the bad boy of quantum mechanics, irreverent, rude and aggressive (modern observers add paedophilia to his list of offences), he derived both the Klein-Gordon equation, although he didn't want to have his name associated with it, and then later his Schrödinger equation, of fantastic simplicity in form and maths, and complexity in meaning:
$$i\hbar\partial_t\Psi=H\Psi$$
Schrödinger rejected quantum mechanics, saying that if the probabilistic interpretation was true, he was sorry he ever had anything to do with it. He is most famous for his eponymous cat, introduced in Ref. [1] (first paper of a series of three, translated in Ref. [2])