It's an interesting one that.
I was chatting about this very thing to a mate over a barbecued sausage over the weekend. There's an argument which says that the most reproduced image is one taken of the Earth by the astronauts onboard Apollo 17.
But I can understand that it had an massive impact in the way we saw the planet, and I imagine that there aren't all that many other options of the Earth from this distance to choose from, and not to be underestimated – it was, as still is, readily available for reproduction. But what I found interesting is that it's not the kind of image which springs to mind as being super common.
The ones that jumped to the fore tended to be the iconic ones like the Raising the flag on Iwo Jima
or Phan Thị Kim Phúc
or a windy Marilyn Monroe
But these are no-doubt in the shadow of the portrait of Che Guevara
and a little black mouse.
But I'm going to challenge the Apollo 17 image of the Earth with the Queen. Of the different media that carry her mug – stamps, coins, banknotes, and err mugs, I think that the coins might be more heavily reproduced than the others as her portrait turns up on the face of all Commonwealth coins, whereas this isn't the case with stamps and banknotes. Of her four coinage portraits I reckon her most recent one by Ian Rank-Broadley used from 1998 might be the most common.
But I'm prepared to be challenged on this...