Have any Black holes actually been observed?
Black holes have only been observed indirectly.
The first black hole was Cygnus X1 which was a galactic radio source which could only be explained by a black hole.
More recently star have been observed at the centre of our galaxy which are moving so fast that they have to be orbiting a body with a mass of 4 mission times that of the Sun which is smaller than the solar system. This can only be a supermassive black hole.