Which artist created the sculpture The Thinker?

Rodin, and it was not conceived as a standalone figure. It was designed as part of The Gates of Hell, an enormous bronze doorway commissioned in 1880 for a museum that was never built, and the seated man was Dante looking down on his own Inferno from the lintel.

Rodin worked on those doors for 37 years and never finished them, and mined them continuously for individual works - The Kiss came out of the same commission and was removed for being too cheerful for the subject. The Thinker was enlarged and cast independently from 1904, and there are now dozens of authorised casts around the world, which is normal for bronze and confuses people who expect an original.

The figure is not contemplating quietly. Every muscle is tensed, the toes grip, the right elbow rests on the left knee in a position no relaxed person adopts - Rodin said he was thinking with every part of his body. That was the argument of his career: that a sculpture should convey internal state through the whole surface rather than through a face and a symbol, which is why his figures look unfinished to eyes trained on classical smoothness and why the Salon repeatedly rejected them.