1800s photographers:
Joseph Niepce
Louis Deguerre
Henry Fox Talbot
Sir John Herschell
Blanquart-Evrard
Frederick Scott Archer
these guys invented processes to make images permanent
some other early photographers that are worth studying:
Alexander Gardner
Roger Fenton
Timothy H. O'Sullivan
there are so many others that have contributed to the history of photography. i'll be back later with some more names