Supermassive black hole from a distance, in the Crown of Othon galaxy
Supermassive black holes are, as their name suggest, a supermassive versions of a black hole. They exist only at the center of each galaxy.
The supermassive black hole may have one or two companion stars, just like a normal solar system.
In supermassive black hole solar systems, interstellar wormholes are instead always around a companion star.
On the event horizon of the supermassive black hole there will be intergalactic wormholes leading to other galaxies.