Scientists recently reconstructed the first model of the prehistoric Kairuku penguin, a species of penguin discovered 30 years ago, but not put back together until now. The Kairuku was over 5 feet tall, had slender hands, and lived for over 25 million years. To contrast, the Emperor penguin, the biggest of the penguin species, is usually around three and a half feet tall.
On a personal note, I think people should fake fear these guys as much as they fake fear clowns. A 5 foot penguin? Come on.