What is it that prompted the United States Postal Service, in honour of Star Wars' 30th anniversary, to dot the country with an army of mailboxes dressed as R2-D2? Well, obviously, he fits the part from a physical standpoint.
But more than that, Artoo remains the most universally cherished character in the Star Wars pantheon and, with the possible exception of Vader's mask, its most potent emblem, doing duty in innumerable universes far, far away from his own, appearing in everything from Sesame Street to Raiders Of The Lost Ark to The Simpsons.
And that's certainly not because he represents anything particularly innovative in droid design. He is, as has been endlessly pointed out, a close relative of the kitchen swing-bin (albeit one of those swanky chrome ones that cost £200 at The Conran Shop, rather than the £8.99 Addis job you bought at Tesco).
He would also seem to be utterly unsuitable for every manner of terrain he encounters. Casters are not what are called for when you spend as much time as Artoo does trundling the desert wastes of Tatooine...
Nevertheless, he is irrepressibly cute, perhaps the only robot in movie history that instils the urge to pet him. Kids adore him because he looks, acts and sounds like the biggest, best toy in the shop.
But for all his cuddly design, Artoo is a useful little fellow. Entrusted with the Death Star blueprints by Princess Leia, he's one of the saga's key players. Courageous and cool-headed, he saves the day on countless occasions while C-3PO stands around dithering like an old woman.
And who among us does not get a lump in their throat when the plucky droid is shanghai'd by Jawas and conks out with a bleepy gurgle so plaintive it could melt the heart of a Coruscanti ogre?