Following set is generally intended when speaking of Beethoven's last string quartets, including the Grosse Fuge (which also exists in a piano transcription, Opus 134):
The quartets were commissioned in 1823 by Prince Nicholas Galitzin, who offered 50 ducats for each opus.
For Grosse Fuge: see also String Quartet No. 13, and of course also P. D. Q. Bach, who composed a Grossest Fugue.