How big a thing was able to land or splash down? Was there ever anything bigger or heavier than the Space Shuttle? If no then whats next on the list? And secondary question: what is the maximal payload which can be returned from orbit (LEO if it matters).
The heaviest space shuttle mission at landing (and an STS Orbiter is by far the heaviest craft to return from space intact) was STS-83 at 235,421 lbs (106,785 kg). This was a Spacelab mission which ended early due to fuel cell problems so it still had a lot of consumables onboard as well as the Spacelab.
Data from Appendix A of the ever-useful Space Shuttle Missions Summary.
The US space shuttle would be the biggest; the Soviet Buran spaceplane would be the runner-up. I think the shuttle could land just about as much payload as it could lift, about 25 tons. (maximum landing weight is 5 tons less than max takeoff weight, but that includes maneuvering fuel).
We don't have that capability any more, of course; I think the only thing we're routinely reentering these days is Soyuz, with three astronauts and a miniscule amount of cargo.
The Orbiter was set to return the Hubble Space Telescope, this was a planned event after the end of Hubble's mission in space. Never happened after Columbia's destruction, that event ended the talk of the Hubble return mission, as well as Shuttle flights.
The Long Duration Exposure Facility was a large payload (9,700 kg); Columbia returned it to earth, having snatched it1 before it burned up on reentry.
The Shuttle design could take 32 tons into low Earth orbit, and return with 16 tons onboard. Those were the targets of the STS (Shuttle) design.
1 Per the linked Wikipedia article: "its orbit had decayed to about 175 nautical miles and it was likely to burn up on reentry in a little over a month."