Falkland Islands Wolf, Hokkaidō Wolf, Honshū Wolf...
Above are three examples of animals that have gone extinct just recently (as far back as the 19th century), due to over hunting and other factors. The Falkland Islands Wolf is a special case, as its disappearance is shrouded in mystery. Anyway, if there was ever an effort by bio-geneticists to revive extinct animals, I would definitely advocate bringing back many species of wolf.
On the topic of "mythical" creatures, might you be referring to
cryptids?