Accretion into black holes is not limited to binary star systems. The adjacent image shows a composite of ground based optical and radio telescope images of the galaxy NGC 4261, and a high resolution Hubble Space Telescope image of the core of this galaxy.
NGC 4261 has enormous jets shooting from its core and very strong radio frequency emission. It is thought that the jets are powered by a gargantuan black hole of perhaps a billion solar masses, and that the ring in the Hubble image is matter swirling around the central black hole.
The black hole itself presumably lies inside the bright spot at the center. Even a billion solar mass black hole would be too small to see in this image.