What Is The Great Attractor?
No; it's real - observations of the movement of galaxies indicate that there is an unusual concentration of mass (probably not a massive "object" of course, but totalling as much as tens of thousands of galaxies) in a place around 200 million lightyears from our galaxy.

It's hard to study since the view in that direction happens to be blocked by our own galaxy, but given that it has been studied for decades, it seems unlikely that the phenomenon turns out to be based on some sort of methodical error.