The General Officer Commanding (GOC) is the usual title given in the armies of the United Kingdom and the Commonwealth (and some other nations, such as Ireland) to a General Officer who holds a command appointment.
A General Officer heading a particularly large or important command, such as Middle East Command or the Allied Armies in Italy, may be called a General Officer Commanding-in-Chief (GOC-in-C). GOC-in-Cs are usually one rank higher than a GOC with GOCs of Corps - level formations reporting into them.
Equivalent Term in other services
The equivalent term for Naval Officers is Flag Officer Commanding (FOC) and that for Air Force Officers is Air Officer Commanding (AOC). In the United States Armed Forces, the equivalent is Commanding General (CG).