Bishop, simple as that. All Bishops are priests including the Pope. ---- A Catholic Answer: Catholics would address a Catholic bishop as "Your Excellency", and one who holds the rank of Cardinal as "Your Eminence."
My experience is that the bishop is simply called, "Bishop".
If you know his surname [let's say it is 'Johnson'], you simply call him, "Bishop Johnson".
You would greet him as "Your Excellency", and then kiss his ring while genuflecting (if he's your Arch/Bishop) or bowing if he is the Arch/Bishop of a Arch/Diocese different than yours.
As of 2006 there were roughly 4,800 bishops. So there is not one Catholic bishop or a bishop who is "the" bishop as your question implies.
Do you mean who is the Catholic Pope?
In that case it's Pope Benedict the XVI.
It is the bishop who is only called by this.
In the Catholic Church most Bishops head a diocese.
There are no female bishops in the Catholic Church so there is no term to describe them.
Only the pope can appoint a bishop in the Catholic Church.
There is no Bishop Weeks in the Catholic Church.
The pope is the bishop of Rome and pope, the earthly head of the Catholic Church.
Pope Benedict XVI is a Bishop of the Catholic Church.
A diocese means a collection of churches that exist in the same geographical region. It is headed by a bishop. The main church is called the Cathedral because it has the bishop's chair in it (called the Catherda) \
In the Catholic Church a Bishop is appointed by His Holiness the Pope.
Bishop
There are just too many to list.
The Pope is the temporal leader of the Catholic Church, and a Bishop has power over a small portion of the world [called a Diocese], but he must ultimately answer to the Pope.