Death's Head Hawkmoth:

http://earthsky.org/earth/lifeform-of-the-week-deaths-head-hawkmoth-is-stranger-than-fiction

My parents have them around their house occasionally, they are impressively massive!

edit: the whole hawkmoth family are impressive - the Elephant Hawkmoth's caterpillar is a bit larger I think, and the Hummingbird Hawkmoth hovers to collect nectar.