I think that we need to coin an official term, "cryptophysicist", to describe people who do physics research outside the mainstream. Ronald Mallett is an example of a credentialed cryptophysicist - he wants to build a time machine using circulating optical beams. His tragic motivations aside, this is a scientifically wacky idea - the energy density that you would need in the beams to produce any significant distortion of spacetime is completely unachievable with foreseeable equipment. On the theory side, Harold Puthoff is another example. Puthoff wants to explain things like inertia in terms of interactions between matter and zero-point fluctuations of the electromagnetic field. Mainstream theorists consider this to be a wacky idea for a long list of reasons.
One major difference between cryptophysicists and cryptozooligists is that the public is generally able to perceive that the latter are outside the mainstream. Everyone knows from daily experience that there probably aren't yeti or sea monsters hanging around. Modern physics is abstracted enough from everyday lives and intuition, though, that many people, including some journalists, honestly can't tell when someone's waaay out there. Also, the concept of the lone genius toiling away in obscurity fighting The Scientific Establishment, which makes for good TV, sounds better when applied to a garage tinkerer than to someone camping out looking for the chupacabra. Still, occasionally the biologists do get to have fun with media coverage of this stuff.