Wikipedia dates this picture of Friedrich Engels to 1840. This seems remarkably early for a surviving photograph (and the photo looks suspiciously clear as well). If the date is correct, could this be the earliest surviving photograph of a notable person, excluding pictures of people involved in developing photography? If not, what is?
I'm sorry to report this isn't a photo. It's from a painting of Engels' time in Manchester. It's also far too clear to be a photo that early. Most photos taken in 1840 were of the recently deceased, since they'd sit still long enough.
1840 sounds about right, though. Daguerreotypy was released to the world in 1839, and was the first form of Photography capable of capturing humans (assuming they were still long enough).
The earliest reliably-dated photo of a person is dated 1838, taken by Daguerre himself and has a 12-minute exposure time.
As to notable people, I can't really contribute. There's a very famous daguerreotype of Arthur Wellesley, 1st Duke of Wellington taken in 1844, but there are probably earlier examples.
