The chacoan peccary in Paraguay, and the giant forest hog in Africa have both been confirmed as real new species. Both of these species are now recognized by science, even though both of them were once the subject of much ridicule.
Another "mythological" giant hog turned out to be a real animal, but it was something other than a pig. This was the pgymy hippo, which looks like a cross between a pig and a miniature hippo.
Likewise, people were ridiculed by "scientists" when they reported sightings of giant sharks. Guess what? Yep. One species, the megamouth shark, has now been declared real by science. Only eleven bodies have been found in the last thirty years and little is known of this shark. The megamouth grows to over fifteen feet long.