There is no place in the universe that is truly empty, but the space be tween clusters of galaxies comes close. Although galaxies continually supply new material to intergalactic space, the continuous expansion of the universe makes the net effect nil.
Intergalactic space is very empty, and it is getting emptier as the universe expands.
The more we learn about it, the more complicated the expansion of the universe seems to be. In the region near our galaxy, the expansion seems less rapid than for the universe as a whole. In fact, it appears that the combined gravitational pull of a very large cluster of galaxies in the constellation Virgo is actually retarding the local rate of expansion to half the rate for the universe as a whole. We're finding evidence of how gravity attracts even over distances of hundreds of millions of light years. Although there must be many very distant galaxies and quasars that we are not yet able to detect, astronomers have observed radiation from an even more remote source, literally at the edge of the observable universe.