The are several examples of stellar mass black holes. There is also indirect evidence that most galaxies have massive black holes in their core. General Theory of Relativity Predicted by Einstein General Theory of Relativity. Bending of light under gravity. Test is shifting of star positions as measured during a solar eclipse.
Modern test is radio wave bending from the Viking transmitter around Mars.
Astronomers have observed double images of quasars. This is due to regular intervening galaxy between the quasar and us. Quasars are very far away galaxies. Perihelion advance of Mercury. 43 arc sec per century.