According to Māori legend the Te Pouākai bird later named as Haast's eagle could swoop down and carry off adults and children.
Weighing up to 18 kilograms, or around three times as much as the wedge-tailed eagle, and with a 3-metre wingspan, it was the largest eagle that has ever lived.
A new study of the animal, that became extinct 500 years ago, shows that it killed like an eagle, but had the table manners of a vulture
"This was undoubtedly the biggest, baddest eagle ever," said zoologist and study co-author Steve Wroe of the University of New England.
The bird's curious mix of features is likely to have developed as a result of its rapid evolution.
"It's probably the most extreme example of rapid evolution in size that we know of in any vertebrate.
"It's basically gone from being a 1-kilo bird to an 18kg bird."
Landing on an island with no predators, it quickly evolved features and behaviours that allowed it to rule the roost.