Beethoven's six "late" string quartets were composed between 1825 and 1826. They are the last major compositions he completed before his death in 1827.
The Quartets are as follows:
String Quartet 12 - Op 127
String Quartet 13 - Op 130
String Quartet 14 - Op 131
String Quartet 15 - Op 132
Grosse Fugue - Op 133
String Quartet 16 - Op 135
Three of the late quartets were commissioned by Prince Nikolai Galitzin (composed in the order 12, 15, 13).
Following the "Galitzin" quartets were the Grosse Fugue, Quartet 14, and Quartet 16.