The Imperial Woodpecker Campephilus imperialis is (or was!) the largest known species of Woodpecker at a whopping 56-60cm. It is (or was!) endemic to the Sierra Madre Occidental Mountains in northern Mexico. It is however now classed at Critically Endangered (possibly extinct) as there hasn't been a confirmed sighting since 1956.
It's an impressive bird with a jet black body, white wings and a white 'V' on the back and a call that apparently sounds like a toy trumpet. Both sexes are crested with the males' being blood red and the females' black. It's a close relative of the also ill fated Ivory-billed Woodpecker of the USA and Cuba.
Recently the Cornell Lab of Ornithology released the only known footage of Imperial Woodpeckers in a remote area of the Sierra Madre recorded by Dr William L. Rhein in the 50's.