The Pantokrator, largely an Eastern Orthodox or Eastern Catholic theological conception, is less common by that name in Western (Roman) Catholicism and largely unknown to most Protestants. In the West the equivalent image in art is known as Christ in Majesty, which developed a rather different iconography. Christ Pantocrator has come to suggest Christ as a mild but stern, all-powerful judge of humanity.
The most common translation of Pantocrator is "Almighty" or "All-powerful". In this understanding, Pantokrator is a compound word formed from the Greek words πᾶς, pas (GENπαντόςpantos), i.e. "all" and κράτος, kratos, i.e. "strength", "might", "power". This is often understood in terms of potential power; i.e., ability to do anything, omnipotence.
Another, more literal translation is "Ruler of All" or, less literally, "Sustainer of the World". In this understanding, Pantokrator is a compound word formed from the Greek for "all" and the verb meaning "To accomplish something" or "to sustain something" (κρατεῖν, kratein). This translation speaks more to God's actual power; i.e., God does everything (as opposed to God can do everything).