The largest one I'm aware of is the Il-62, with a whopping 4 turbofans at its tail. Max takeoff weight is 165 tons.
I actually don't care how many engines there are, as long as all are at the tail. I don't care what kind either, turbofans, turbojets, anything. Don't care if it's military or civilian.
Edit: Airbreathing engines only. The space shuttle and buran don't go above 109 tons anyway, but the criteria here is max takeoff weight and those rockets "take off" far too differently than airplanes.
I googled this of course, but predictably these kinds of "what's the biggest" questions with specific conditions attached are not well-known. I'm hoping someone will know of an example bigger than 165 tons.
The reason I ask is because I'm curious just how much engine weight can be put at the tail and still have a conventionally-shaped aircraft. I'm a little surprised at the Il-62, actually. Sooner or later, to keep the center of mass ahead of the center of drag, the wings have to move more and more back until suddenly you have a canard config where the wings almost operate like a delta where the ailerons are also elevons and maybe even flaps.