In philosophy, the GCB is the greatest conceivable being, used in discussion of ontology.
In the British honours system, a GCB is a "Knight Grand Cross" in the Order of the Bath.
GCB is the Germany Convention Bureau, http://www.gcb.de.
GCB is also the German Conference on Bioinformatics.
In Ghana, 'GCB'\ is the Ghana Commercial Bank, http://www.gcb.com.gh.
In Nevada, the Gaming Control Board (GCB) regulates gambling in the state.
In Minnesota, GCB is the Minnesota Gambling Control Board, which regulates gambling in the state; http://www.gcb.state.mn.us.